i^^^ 


NORTH  CAROLINA  STATE  UNIVERSITY  LIBRARIES 


S02811864  U 


This  book  is  due  on  the  date  indicated  unless 
recalled  by  the  Libraries.  Books  not  returned  on 
time  are  subject  to  replacement  charges. 
Borrowers  may  access  their  library  accounts  at: 
http://www.lib.ncsu.edu/ads/borrow.html 


THE 
BOTANY  OF  CROP  PLANTS 


ROBBINS 


THE 

BOTANY  OF  CROP  PLANTS 

A  TEXT 
AND  REFERENCE  BOOK 


BY 

WILFRED  W.  ROBBINS,  Ph.  D. 

PROFESSOR  OF  BOTANY,  COLORADO  AGRICULTURAL  .'tJLLEGE 


WITH  A  GLOSSARY  AND 
263  ILLUSTRATIONS 


PHILADELPHIA 
P.   BLAKISTON'S  SON  &  CO, 

1012  WALNUT  STREET 


Copyright,  1917,  by  P.  Blakiston's  Son  &  Co. 


THE  MAPLE  PRESS  VORK  PA 


PREFACE 

This  book  has  grown  out  of  a  course  of  instruction  ex- 
tending over  a  number  of  successive  years.  Most  of  the 
material  presented  here,  except  Part  I,  has  been  used  in 
mimeographed  form  in  college  freshmen  classes,  not  only  as 
a  text  from  which  to  make  assignments,  but  also  as  a  guide 
and  reference  in  the  laboratory.  The  issuance  of  the  book 
has  been  stimulated  in  part  by  the  expressed  need  of  a  number 
of  schools  for  a  text  and  reference  book  which  will  give  the 
student  a  knowledge  of  the  botany  of  common  orchard, 
garden  and  field  crops,  and  it  is  the  author's  wish  that  the 
material  brought  together  from  many  sources  and  organized 
in  the  present  form  will  meet  this  need,  at  least  in  a  measure. 

It  has  seemed  advisable  to  include  chapters  (Part  I)  which 
may  be  needed  in  some  instances  to  refresh  the  student's 
knowledge  of  certain  fundamentals,  or  prepare  him  for  that 
which  follows  in  Part  II.  But  in  many  schools  Part  II  will 
be  preceded  by  a  general  course  which  aims  to  give  the  stu- 
dent a  survey  of  the  plant  kingdom  and  an  acquaintance  with 
the  large  outstanding  facts  and  principles  of  botany,  and  in 
this  case  Part  I  will  be  omitted.  The  subject  matter  of 
Part  II  is  sufiicient  for  a  course  of  one-half  year  involving 
one  recitation  and  two  laboratory  (5)  periods  per  week. 

In  the  preparation  of  the  book,  the  writer  has  had  in 
mind  non-agricultural  as  well  as  agricultural  schools,  for  it 
cannot  escape  notice  that  there  is  a  growing  tendency, 
wherever  botany  is  taught,  to  tie  it  up  more  closely  with 
economic  interests  and  to  draw  more  and  more  upon  economic 
plants  in  citing  examples  and  in  choosing  objects  of  study  in 
the  laboratory. 


VI  PREFACE 

The  bibliographies  are  obviously  incomplete.  Most  of  the 
titles  were  made  use  of  by  the  writer  in  the  preparation  of  the 
manuscript,  and  to  the  authors  of  these  he  is  under  obliga- 
tion. Bailey's  Cyclopedia  of  Horticulture  has  been  indis- 
pensable and  has  been  called  into  use  frequently.  The 
writer  has  also  called  upon  the  publications  of  the  United 
States  Department  of  Agriculture  and  of  the  various  Experi- 
ment Stations.  A  number  of  the  "keys"  are  original, 
many  are  adapted,  and  a  few  are  taken  verbatim.  A 
majority  of  the  illustrations  are  original.  It  is  believed  that 
the  direct  method  adopted  herein  of  labeling  drawings  will 
appeal  to  both  students  and  teachers. 

Almost  all  original  illustrations,  and  also  those  copied  or 
adapted  are  the  work  of  Mr.  N.  Lee  Foster.  The  writer  is 
especially  indebted  to  him,  not  only  for  the  delineation,  but 
for  his  helpful  interest  and  valued  cooperation  throughout. 
Professor  D.  W.  Frear,  formeily  Associate  Professor  of 
Agronomy  at  the  Colorado  Agricultural  College,  now  of  the 
North  Dakota  Experiment  Station,  is  to  be  given  credit  for 
organizing  and  writing  up  portions  of  Chapters  IX,  XVII, 
XXX  and  XXXVIII.  The  text  was  planned  and  outlined 
by  Professor  Frear  and  the  undersigned  as  joint  authors, 
but  unavoidable  exigencies  made  it  impossible  for  him  to 
continue  his  connection  as  author.  The  entire  manuscript 
was  painstakingly  read  by  Louise  Falk  Robbins,  and  her 
suggestions  have  added  greatly  to  the  accuracy  in  many 
places, 

W.  W.  Robbins. 

Colorado  Agricui-tural  College 


CONTENTS 

PART  I 

CHAPTER  I.— The  Seed  Plant  Body. 

Principal  Parts  of  the  Seed  Plant  Body — Size  and  Form  of  the 
Seed  Plant  Body 1-3 

CHAPTER  II. — Fundamental  Internal  Structxjre  of  Plant  Body. 
Organs'^and  Tissues— The  Plant  Cell— The  Cell  as  a  Unit  of 
Structure— The  Cell  as  a  Unit  of  Plant  Activity— The  Struc- 
ture of  the  Plant  Cell— The  Cell  Wall— Plastids— Nucleus- 
Protoplasm  4-9 

CHAPTER  III.— Roots. 

Development  of  Root  Systems — The  Work  of  Roots — Effect 
of  Environment  upon  Character  of  Root  System — General 
Characteristics  of  Roots — Classification  of  Roots  Based  upon 
Their  Medium  of  Growth — Structure  of  Roots — Root  Hairs, 
the  Absorbing  Organs  of  a  Plant — Root-hair  Zone — Structure 
of  a  Root  Hair — Effect  of  E.xternal  Factors  upon  Develop- 
ment of  Root  Hairs — ^Length  of  Life  of  Roots 10-21 

CHAPTER  IV.— Stems. 

Development  of  Shoot  System — Buds— Classification  of 
Buds — Bud  Variation — General  Characteristics  of  Stems — 
How  Does  a  Stem  Grow  in  Length — Classification  of  Stems 
Based  upon  Their  Medium  of  Growth — "Modified"  Stems — 
Structure  of  Stems — The  Young  Dicot  Stem — Dicot  Vas- 
cular Bundle— Growth  in  Thickness  of  Dicot  Stem—  Monocot 
Stems— Annual  Rings — Bark — The  Work  of  Stems 22-41 

CHAPTER  v.— Leaves. 

Development  of  Leaves — Parts  of  Leaf — Kinds  of  Leaves — 
*    Structure  of  Leaves — The  Work  of  Foliage  Leaves 42-47 

CHAPTER  VI.— Flowers. 

Parts  of  Representative  Flower — Development  of  the  Flower 
— Stamens — Mature  PoUen  '  Grain — Pistil — Ovule — Pollina- 
tion— Fertilization — Placentation — Symmetry  of  Flower — 
Relative  Positions  of  Flower  Parts — Union  of  Flower  Parts — 
Incomplete  Flowers — Inflorescence 48-56 

CHAPTER  VII.— Fruits,  Seed,  and  Seedlings. 

Development  of  the  Seed — Development  of  the  Fruit — Fruit 
and  Seed  Distinguished — Kinds  of  Fruits — Germination  of 

the   Seed 57-59 

vii 


VIU  CONTENTS 

CHAPTER  VIII. — The  Classification  and  Naming  of  Plants. 
Reproductive  versus  Vegetative  Organs  in  Classification — 
Groups  of  Plants — The  Plant  Kingdom — Plant  Nomenclature 
— Scientific  Name — Scientific  Name  versus  Common  Name — 
General  References 60-67 


PART  II 

CHAPTER  IX.— GRAMiNEiE  (P0ACE.E)  Grass  Family. 

Habit  of  Plants — Roots — Stems — ^Lodging— Tillering — Bulb- 
ous Grasses — Rhizome-bearing  Grasses — Stoloniferous 
Grasses — ^Leaves — Growth  of  Leaves — Scales  and  Bracts — 
Ligule — Auricle — Inflorescence — Spikelet — Pollination — Fruit 
— Phylogeny  of  Grasses — Grass-like  Plants — References — 
Cereals — Key  to  Groups  of  Important  Cereals — Key  to  Small- 
grain  Seedlings — References 68-90 

CHAPTER  X.— Triticum  (Wheat). 

Habit  of  Plant — Roots — Stems — ^Leaf — Inflorescence — Spike- 
let — Flower — Opening  of  Flower  and  Pollination — Artificial 
Cross  Pollination — Fertilization  and  Maturing  of  Grain — 
Ripening  Stages — The  Mature  Grain — Relative  Proportions  of  • 
the  Parts  of  the  Grain— "Hard"  and  "Soft"  Wheats— Milling 
of  Wheat — Kinds  of  Flour — Germination  of  Wheat — Classi- 
fication of  the  Types  of  Wheat — Key  to  Economic  Types  of 
Wheat — Origin  of  Wheat — Environmental  Relations — Uses  of 
Wheat — Production  of  Wheat — References 91-1 21 

CHAPTER  XI.— AvENA  (Oats). 

Habit  of  Plant— Roots— Stems — ^Leaf— Inflorescence— Spike- 
let  and  Flower — Opening  of  Flower  and  Pollination — Fertiliza- 
tion and  Maturing  of  Grain — The  Mature  Grain — Germina- 
tion of  Oats — Classification  of  Oats— Other  Cultivated  Oats 
— A  vena  fatua  ("wild  oats") — Origin  of  Oats — Environmental 
Relations — Uses  of  Oats — The  Production  of  Oats  — 
References .' 122-134 

CHAPTER  XII.— HoRDEUM  (Barley). 

Habit  of  Plant,  Roots,  Stems,  Leaves — Spikelet  and  Flower — 
Opening  of  Flower  and  Pollination — Fertilization  and  Matur- 
ing of  Grain — Mature  Grain  of  Barley — Color  of  Grain- 
Germination  of  Barley — Classification  of  Barleys — Origin 
of  Cultivated  Barleys — Environmental  Relations— Uses  of 
Barley — The  Brewing  Process — Production  of  Barley- 
References  135-152 


CONTENTS  IX 

CHAPTER  XTII.— Secale  cereale  (Rye). 

Habit  of  Plant,  Roots — Steins,  Leaves — Inflorescence — Spike- 
let — Opening  of  Flower,  Pollination  and  Fertilization — Matur- 
ing of  Grain,  and  Mature  Grain — Germination  of  Rye — 
Classification,  and  Origin  of  Rye — Environmental  Relations 
—Uses  of  Rye— Production  of  Rye— References iS3-i56 

CHAPTER  XIV.— Zea  (Corn,  Maize). 

Habit  of  Plant,  Roots— "Prop"  and  "Brace"  Roots— Stem 
—Leaves — Inflorescence— Staminate  Inflorescence — Stami- 
nate  Spikelet — Pistillate  Inflorescence — Pistillate  Spikelet — 
Hermaphroditic  Flowers — Opening  of  the  Flowers,  and  Pollina- 
tion— Fertilization,  and  Development  of  the  Grain — ^Xenia 
in  Corn  —Variation  in  the  Corn  Plant — Results  of  Self-fertiliza- 
tion in  Corn — The  Mature  Grain  of  Corn — Corn  Starch 
Distinguished  from  the  Other  Common  Starches — Germina- 
tion of  Corn — Classification — Key  to  "Species  Groups"  of 
Corn — Origin  of  Maize — Environmental  Relations — Uses  of 
Corn — Production  of  Corn — References 157-190 

CHAPTER  XV. — Andropogon  Sorghum  (Sorghums). 

Habit  of  Plant,  and  Roots — Stems  and  Leaves — Inflorescence 
— Spikelets  and  Flowers — Fertile  Spikelet — Staminate  Spike- 
let— Opening  of  Flowers  and  Pollination — Fruit — Varieties — 
Key  to  Principal  Groups  of  Sorghum — Origin  of  Sorghums — 
Environmental  Relations — Uses  of  Sorghums — References.  .191-201 

CHAPTER  XVI.— Oryza  sativa  (Rice). 

Habit,  Roots,  Stems,  Leaves — Inflorescence  and  Spikelet — 
Pollination  and  Fertilization — Grain — Milling  of  Rice— : Varie- 
ties— Distribution,  and  Closely  Related  Species — Uses  of  Rice 
— Environmental  Relations — The  Production  of  Rice — 
References 202-209 

CHAPTER  XVIL— Millet. 

Key  to  Principal  Economic  Types  (Species)  of  Millet  and 

Some  Closely  Related  Common  Weed  Grasses 210-211 

Pennisetum  glaucum  (Pearl  Millet) — Stem — ^Leaf— Inflores- 
cence— Spikelet   and   Flower — Pollination — Mature   Grain — 

Varieties — Origin 211-213 

Panicum  miliaceum  (Proso,  Hog  or  Broom-corn  Millet) — 
Stem — ^Leaf — Inflorescence — Spikelet  and  Flower — Pollina- 
tion— Mature  Grain — Varieties — Origin 213-216 

Chaetochloa  italica  (Foxtail  Millets) — Steam — ^Leaf —Inflores- 
cence— Spikelets  and  Flower — Pollination — Mature  Grain- 
Types  and  Varieties  of  Foxtail  Millet — Key  to  Principal  Types  of 
Foxtail  Millets  (Chaetochloa  italica) — Origin  of  Foxtail  Millet.  216-219 


X  CONTENTS 

Echinochloa  Crus— galH  (Barnyard  Grass  or  Barnyard 
Millet) — Habit,      Stems,     Leaves — Inflorescence,     Spikelet, 

Flowers,  and  Fruit — Distribution 219-220 

Echinochloa  frumentacea  (Japanese  Barnyard  Millet) 219-220 

En\nronmental  Relations — Uses  of  Millets — References 220-221 

CHAPTER  XVIII.— Phleum  pratense  (Timothy). 

Description — Environmental  Relations — Closely  Related  Spe- 
cies— References 222-224 

CHAPTER  XIX.— Saccharum  officinarum  (Sugar  Cane). 

Habit,  Roots — Stems — ^Leaves — Inflorescence,  Flowers,  Fruit 
— Geographical — Sugar  from  Sugar  Cane — Production  of  Cane 
Sugar 225-228 

CHAPTER  XX.— Liliace^  (Lily  Family). 

Habit,  Roots — ^Leaves — Inflorescence  and  Flowers — Fruit  and 

Seeds 229-230 

Allium — Roots — Stems — Leaf — Inflorescence — Flower — Polli- 
nation— Fruit — Germination  of  Seed,  and  the  Seedling — 
Geographical— Key  to  the  Principal  Cultivated  Species  of 

Genus  Allium 231-237 

Allium  sativum  (Garlic) 237 

Allium  porrum  (Leek) 238 

Allium  schcenoprasum  (Chives  or  Gives) 238 

Allium  ascalonicum  (Shallot) 238-239 

Allium  fistulosum  (Welsh  Onion  or  Ciboule) 239-240 

Allium  cepa  (Onion) — Description — History — Types  of  Onions 
— Foreign  and  Domestic  Onions — Composition  of  Onions — 

Uses  of  Onions 240-244 

Asparagus — Generic    Description — Economic   Importance    of 

Genus 244-246 

Asparagus  ofl&cinalis  (Asparagus) — Roots — Stems — ^Leaf — 
Flower— Pollination— Fruit — Geographical — Types  and  Va- 
rieties— References 246-251 

CHAPTER  XXL— MoRACE^  (Mulberry  Family). 

Description — Key  to  Principal  Genera 252-253 

Moms  (Mulberry)— Habit,  Stems — Leaves — Inflorescences — 
Fruit— Other  "Mulberries"— Geographical— Key  to  Principal 

Species  of  Genus  Morus 253-255 

Morus  alba  (White  Mulberry) — Description — Geographical 
— Types  and  Varieties — Economic  Importance — Early  At- 
tempts in  the  United  States  to  Grow  Silk— Uses 255-257 

Morus  nigra  (Black  Mulberry) — Description^ — Geographical 

—Varieties— Uses 257-258 

Morus  rubra  (Red  Mulberry)— Description — Geographical- 
Varieties  and  Uses 258 


CONTENTS  XI 

Humulus  (Hop).  Humulus  lupulus  (Common  Hop) — Root — 
Stems — Leaves — Inflorescences — Flowers — Pollination,  Fertili- 
zation, and  Development  of  the  "Hops" — The  Mature  Fruit — 
Lupulin   Glands — Geographical — Closely    Related   Species — 

Varieties — Composition — Uses  of  Hops 258-267 

Ficus  (Fig) — Habit,  Roots,  Stems — Leaves — Inflorescence — 

Geographcal  Distribution,  and  Economic  Importance 267-269 

Ficus  cariica  (Common  Fig) — Habit  of  Plant,  and  Stem — 
Leaves — Inflorescence,  and  Flowers — Pollination — Crops  of 
Fruit  in  Caprifigs — Caprification — The  Mature  Fruit — Geo- 
graphical— Types  of  Figs — Uses  of  Figs 269-276 

Cannabis  sativa  (Hemp) — Description — Geographical — Varie- 
ties— The  Hemp  Industry  in  the  United  States — Preparation 
of  Hemp  for  Market — Uses  of  Hemp — Sisal  Hemp — 
References 276-283 

CHAPTER  XXIL— PoLYGONACE^  (Buckwheat  Family). 

Stems — Inflorescences — Flowers — Fruit — Key     to     Principal 

Genera 284-286 

Rheum  rhaponticum  (Rhubarb,  Pie  Plant) — Roots,  Stems, 
Leaves,     Flowers  —  Fruit  —  Geographical,    and    Varieties  — 

Uses 286-289 

Fagopyrum  vulgare  (Common  Buckwheat) — Roots — Stems — 
Leaves — Inflorescence — Flowers — Dimorphism  and  Pollina- 
tion— Fruit — Seed — Geographical — Other  Species — Varieties 
— Key  to  Varieties  of  Common  Buckwheat — Environmental 
Relations — Uses — References 289-295 

CHAPTER  XXIII. — CHENOPODiACEiE  (GoosEFOOT  Family). 

Habit,  Stems,   Leaves — Inflorescence   and  Flowers — Fruit — 

Key  to  Principal  Genera 296-298 

Spinacia  oleracea  (Spinach)— Description — Other  Plants 
Named  "  Spinach" — Groups  of  True  Spinach — Key  to  Groups 

of  Spinach 298-300 

Beta  vulgaris  (Beet) — Botanical  Groups — The  Wild  Beet. .  .300-301 
Sugar  Beet — Habit — Root — Stems — Shape  and  Structure  of 
Beet  (Tap  Root  and  Hypocotyl) — ^Leaves — Inflorescence — 
Flowers — Pollination  and  Fertilization — Fruit  and  Seed — 
Seed  Production — Germination,  and  the  Seedling — Types  of 
Sugar  Beets — Composition  of  Sugar  Beets — Manufacture  of 

Sugar — By-products  of  Manufacture 301-309 

Common  Garden  Beet— Types — Uses 310-312 

Chard 312  313 

Mangel-wurzels      or      Mangels — Types — Composition      and 

Uses — References 313-315 


XU  CONTENTS 

CHAPTER  XXIV.— Geossulariace^  (Gooseberry  Family). 

Stems — Leaves — Inflorescence  and  Flowers — Pollination — 
The  Mature  Fruit — Seeds — Geographical — Key  to  Important 

Species  of  Genus  Ribes  316-319 

Currants — Species — Uses 320-321 

Gooseberries — Species — Uses  321-322 

CHAPTER  XXV.— Crucifer^  (Mustard  Family). 

Stems,  Leaves — Inflorescence  and  Flowers — Fruit — Seeds — 

Closely  Related  Families — Key  to  Principal  Genera 323-326 

Brassica —Generic  Description — Pollination — Seedling — Geo- 
graphical— Key  to  Principal  Species  of  Genus  Brassica 327-328 

Brassica  oleracea  (Cabbages,  etc.) — Wild  Cabbage — Cultivat- 
ed Types  of  Cabbages— Key  to  Cultivated  Types  of  Cabbage. 328-330 

Brassica  oleracea  var.  viridis 330 

Brassica  oleracea  var.  gemmifera  (Brussels  Sprouts) — Types 

— Uses 330-33^ 

Brassica  oleracea  var.  capitata  (Common  Head  Cabbage) — 

Types — Key  to  Types  of  Head  Cabbage — Uses 331-33.3 

Brassica  oleracea  var.  caulo-rapa  (Kohlrabi  or  Turnip-rooted 

Cabbage) 333 

Brassica  oleracea  var.  botrytis  (Cauliflower,  Broccoli) 334-335 

Brassica  rapa  (Turnip) — Description — Geographical — Types 

of  Turnips— Structure  and  Uses 335-337 

Brassica  campestris  (Rutabaga  or  Swede  Turnip) — Descrip- 
tion—Uses  337-338 

Brassica  napus  (Rape) — Description — Varieties  and  Uses.  .  .338-339 
Brassica  nigra   (Black  or  Brown  Mustard) — Description — 

Related  Species — Uses 339-34° 

Brassica  alba  (White  Mustard) 340-341 

Raphanus  sativus  (Garden  Riadish) — Habit— Root— Stem- 
Leaves — Inflorescence  and  Flowers — Fruit — Seeds  and  Seed- 
ling—Geographical Distribution  and  Origin — Closely  Related 

Species — T3^es  of  Radishes 341-344 

Radicula  (Water  Cress  and  Horse-radish) 344-345 

Radicula  armoracia  (Horse-radish) — Description — Geograph- 
ical— Uses 345 

Radicula  nasturtium-aquaticum  (Water  Cress) — Description 

— Geographical — References 345-347 

CHAPTER  XXVI.— Rosacea  (Rose  Family). 

Leaves — Inflorescence — Flowers — Fruit — Key    to    Important 

Genera  of  Rosaceae 348-35° 

Rubus  (Raspberry,  Blackberry,  Dewberry)  —  Stems  — 
Propagation — ^Leaves — Inflorescence — Flowers — Pollination — 


CONTENTS  Xlll 

Fruit — Geographical — Classification — Key  to  Groups  of  Genus 

Rubus 350-354 

Blackberries — Key  to  Species  of  Blackberries — Rubus  nigro- 
baccus — Rubus  nigrobaccus  X  R.  villosus — Rubus  argutus — 

Rubus  cuneifolius 354-355 

Dewberries — Key  to  Principal  Species  of  Dewberries — Rubus 
trivialis — Rubus  invisus — Rubus  vitifolius — Rubus  villosus.  .355-357 
Raspberries — Key  to  Principal  Species  of  Raspberries — Rubus 
occidentalis — Rubus    idaeus — Rubus   strigosus — Rubus   stri- 

gosus  X  R.  occidentalis — The  Loganberry — Mayberry 355-358 

Fragaria  (Strawberry) — Roots  and  Stems — Leaves — Inflores- 
cence and  Flowers— Fertilization,  and  Development  of  the 
Fruit — The  Mature  Fruit — Geographical — Principal  Fruit- 
bearing  Species — Key  to  Principal  Species  of  Fragaria — 
Fragaria  virginiana — Fragaria  vesca — Fragaria  chiloensis — 
Varieties — Origin  of  New  Varieties — Uses — References 358-365 

CHAPTER  XXVIL— Pomaces  (Apple  Family). 

Habit,  Leaves — Inflorescence — Flowers — Fruit — Geographical 

— Key  to  Important  Genera  of  Pomaceae 366-367 

Malus  (Apples) — Stems — ^Leaves — Inflorescence — Flowers  and 
Their  Development — Pollination  and  Fertilization — Self- 
.  sterility  and  Self-fertility— Effects  of  Strange  Pollen— Par- 
thenocarpy — The  Fruit  and  Its  Development — Key  to  Principal 
Species  of  Malus — Malus  floribunda — Malus  baccata — Malus 
angustifolia — Malus  coronaria — Malus  ioensis— Malus  soul- 
ardii — Malus  sylvestris — The  Classification  of  Apples — Com- 
position— Cider  and  Vinegar — Dried  Apples — Production  of 

Apples  in  the  United  States 367-384 

Pyrus  (Pear)  384 

Pyrus     communis     (Common     Pear) — Stem — ^Leaves     and 

Flowers — Fruit — Geographical 385 

Pyrus  serotina  culta  (Sand,  Japanese,  or  Chinese  Pear) — Self 

-sterility  in  Pears — Dwarf  Pears 385-387 

Cydonia  (Quince) —Cydonia  oblonga  (Common  Quince) — 
Stem — ^Leaves —  Flowers  —  Fruit — Varieties  —  Uses  —  Refer- 
ences  387-390 

CHAPTER  XXVIIL— Drupace^  (Plum  Family). 

Habit,  Stems — Leaves — Flowers — Fruit 391-394 

Prunus — Key  to  Main  Groups  of  Genus  Prunus 394 

Plums — Stems — ^Leaves — Inflorescence — Flowers— Fertiliza- 
tion— Fruit — Classification    of     Plums — Key    to     Principal 

Species  of  Plums 394-397 

Discussion  of  Species — Prunus  domestica — Prunus  insititia— 


XIV  CONTENTS 

Prunus     cerasifera — Prunus     triflora— Prunus     americana— 

Prunus  hortulana — Prunus  nigra — Prunus  angustifolia 398-401 

Cherries — Description — Groups  of  Cherries 401-402 

Prunus   avium    (Sweet    Cherry) — Description — Geographical 

— Groups  of  Sweet  Cherries 402-403 

Prunus  cerasus  (Sour  Cherry) — Description — Geographical — 
Groups  of  Sour  Cherries — Other  Species  of  Cherries — Uses .  .  .  403-405 
Apricots — Stems — ^Leaves — Inflorescence  and  Flowers — Fruit 

— Description — Other  Species — Uses 405-407 

Peaches — Stems — Leaves — Inflorescence  and  Flowers — Fruit 
— Geographical — Types  of  Peaches — Uses,  and  Production  of 

Peaches  in  the  United  States 407-410 

Almonds — Description — Types   of   Almonds — UscSt— Almond 

Oil— References .410-412 

CHAPTER  XXIX.— Leguminos^  (Pea  Family). 

Root  Tubercles— Habit — ^Leaves  —Inflorescence — Flowers — 

Fruit — Seeds — Key  to  Principal  Genera  of  Leguminosae 413-417 

Pisum  (Pea) — Description — Types  of  Peas — Peas  and  Men- 

delism — Uses 41 7-421 

Phaseolus  (Bean) —Description — Geographical,  and  Species — 

Key  to  Principal  Species  of  Phaseolus 421-424 

Phaseolus  lunatus  (Sieva  and  Lima  Beans) — Classification  of 
Types  of  Lima  Beans— Table  Showing  Relationship  of  Types  of 

Lima  Beans 424-426 

Phaseolus  vulgaris  (Kidney  Bean) — Uses  of  Beans 426 

Vicia  (Vetch,  Broad  Bean) — Generic  Description — Geographi- 
cal— Key    to    Important    Species    of    Vicia — Less    Common 

Species 426-429 

Vicia  faba  (Broad  Bean,  Windsor  Bean) 429 

Vicia  sativa  (Common  Vetch  or  Tares)— Uses 429-430 

Vicia  villosa  (Hairy,  Russian,  Siberian,  or  Villous  Vetch) 430-432 

Lathyrus  (Vetchling,  Wild  Pea) ■ 432 

Trifolium  (Clover) — Generic  Description — Geographical- 
Key  to  Principal  Species  of  Trifolium 432-433 

Trifolium  repens   (White  or  Dutch  Clover) — Description — 

.     Geographical,  and  Uses — Environmental  Relations 433-434 

Trifolium  hybridum  (Alsike,  Alsatian,  or  Swedish  Clover)  — 

Description — Geographical,  and  Uses. 434-435 

Trifolium  incarnatum  (Crimson,  Scarlet,  or  Italian  Clover)  — 
Description — Geographical,  and  Uses — Environmental  Rela- 
tions   435-436 

Trifolium  pratense  (Common  Red  or  Purple  Clover) — 
Habit,  Stems,  Roots — ^Leaves — Inflorescence  and  Flowers — 


CONTENTS  XV 

Fruit— Pollination — Geographical — Environmental  Relations 

—Mammoth  Clover — Uses 436-440 

Trifolium  medium  (Zigzag,  Medium  Red,  "White,  Mammoth 

or  Meadow  Clover) 44i 

Medicago  (Medics) — Generic  Description — Geographical- 
Key  to  Principal  Species  of  Medicago 441-442 

Medicago  sativa  (Alfalfa,  Lucerne) — Roots — Stems — "Cut- 
tings" of  Alfalfa— Leaves — Inflorescence — Flowers — Pollina- 
tion— Factors  Affecting  Seed  Production — Fruit — Germina- 
tion and  Seedling — Geographical — Types  of  Alfalfa — Environ- 

.  mental  Relations — Uses  and  Production 442-449 

Medicago  lupulina  (Hop  Clover,  Black  Medic,  Yellow  Trefoil)  .449 

Medicago  arabica  (Spotted  Bur  Clover) 449-451 

Medicago  hispida  (Toothed  Bur  Clover) 452 

Melilotus   (Sweet  Clover) — Generic  Description — Species  of 

Melilotus 452-454 

Melilotus  alba  (White  Sweet  Clover) — Description 454 

Melilotus  ofhcinalis  (Yellow  Sweet    Clover) — Description — 

Environmental  Relations — Uses  of  Sweet  Clovers) 454-455 

Soja  (Soy  Bean) — Generic  Description 455-456 

Soja  max  (Soy  Bean,  Soja  Bean,  Coffee  Bean) — Description — 

Uses 456-458 

Vigna  (Cowpea  and  Related  Species) — Description— Species..458-46o 
Vigna  sinensis  (Cowpea) — Description — Environmental  Rela- 
tions— Uses 460-462 

Arachis  hypogoea  (Peanut,  Goober) — Habit,  Stem — ^Leaves — 
Flowers — Development  of  Fruit — Fruit — Types — Environ- 
mental Relations 462-465 

Less  Important  Legumes 465-467 

References 467-468 

CHAPTER  XXX.— Linages  (Flax  Family) 

Habit,  Stem,  Leaf — Inflorescence  and  Flowers^Fruit — The 
Names  Derived  from"Linum" — Geographical,  and  Environ- 
mental Relations 469-470 

Linum  usitatissimum  (Common  Flax) — Habit,  Root — Stem — 
Flax  Fibers— Leaves,  Inflorescence  and  Flowers — Pollination 
— Mature  Fruit — Seeds — Geographical — Types  and  Varieties 
— Uses — Preparation  of  Flax  Fiber — Production  of  Flax 470-474 

CHAPTER  XXXI.— Rutace^  (Rue  Family). 

Description — Key  to  Important  Genera  of  Rutaceae 475-476 

Citrus  (Citron,  Lemon,  Orange,  etc.) — Habit,  Roots — ^Leaves 
— Flowers — Pollination  and  Fertilization — Fruit — Seeds — 
Geographical — Key  to  Principal  Species  of  Citrus 476-480 


XVI  CONTENTS 

Citrus  medica  (Citron) — Description — Geographical — "  Cit- 
ron"  480-481 

Citrus  limonia  (Lemon) — Description — Geographical — Color 

of  Lemon  Fruit — Uses 481-483 

Citrus      aurantifolia      (Lime) — Description— Geographical — 

"Limequat" 483 

Citrus  sinensis  (Common  or  Sweet  Orange) — Description — 

Geographical — Types — Uses 484-485 

Citrus  nobilis  (King  Orange) — Description — Varieties ,485 

Citrus  grandis  (Grapefruit,  Pomelo,  Shaddock) — Description 

— Geographical— Variety  and  Name 485-487 

Citrus  aurantium   (Sour  or  Seville  Orange) — Description — 

Geographical — Other  Species  of  Citrus.; 487 

Fortunella    (Kumquat   or    Kinkan) — Description — Species — 

Uses 487-489 

Poncirus  (Trifoliate  Orange) — Description — A  Hardy  Grange.489 
References 489-490 

CHAPTER  XXXII.— ViTACE^  (Grape  Family). 

Family      Description — Geographical — Key      to      Important 

Genera 491-492 

Vitis  (Grape) — Stems — ^Leaves — Inflorescence  and  Flowers — 
Opening  of  Flower  and  Pollination — Self-sterility — Grape 
Pollen — "Coulure"  of  Muscat  Grape — Flowers  of  Wild  Grape 
— Key  to  Most  Important  Species  of  Vitis — Vitis  vinifera — 
Vitis  rotundifolia — Vitis  rupestris — Vitis  riparia — Vitis  aesti- 
valis— Vitis  labrusca — Varieties  of  Table  Grapes — Wine  and 
Raisin  Grapes — Uses — References 492-504 

CHAPTER  XXXIIL— Malvace^  (Mallow  Famly). 

Habit — Leaves — Flowers^-Fruit  and  Seeds — Geographical — 
Economic  Importance — Key  to  Important  Genera  of  Mal- 
vaceae  5oS~So8 

Gossypium  (Cotton) — Habit  of  Plants,  and  Roots — Stems — 
Leaves — Flowers — Pollination,  Fertilization,  and  Development 
of  the  Fruit — Fruit — Seeds — Cotton  Fibers  Distinguished  from 
Other  Common  Textile  Fibers — Species — Wild  Cottons — 
American  Cottons — Types  and  Varieties — Environmental 
Relations — Picking  and  Ginning  of  Cotton — Bleaching  of 
Cotton — Uses    of    Cotton — Importance    and    Production    of 

Cotton 508-527 

Hibiscus  esculentus  (Okra,  Gumbo) — Description — Geo- 
graphical— Types — Uses 527-528 

References 528-529 


CONTENTS  XVll 

CHAPTER  XXXIV.— UMBELLiFEEiE  (Carrot  Family). 

Stems    and    Leaves — Inflorescence     and     Flowers — Fruit — 

Geographical — Key  to  Genera  of  Economic  Importance S3o~S33 

Daucus  carota  (Carrot) — Habit,  Root  and  Stems — ^Leaves — 
Inflorescence   and    Flowers — Fruit   and   Seed — Geographical 

— Varieties — Uses 533-536 

Pastinaca  sativa  (Parsnip) — Habit,  Roots,  and  Stems — ^Leaves 
— Inflorescence  and  Flowers — Fruit  and  Seed — Geographical 

— Varieties S36-538 

Apium  (Celery  and  Parsley) — Generic  Description — Geo- 
graphical— Key  to  Principal  Species  of  Apium 53^-539 

Apium  petroselinum  (Parsley) — Description — Varieties 539-54° 

Apium  graveolens  (Celery  and  Celeriac) — Description — Geo- 
graphical— Types  and  Varieties — Uses 540-542 

References 542 

CHAPTER  XXXV.— Vacciniace^  (Huckleberry  Family). 

Habit — ^Leaves — Inflorescence  and  Flowers — Fruit 543-545 

Vaccinium — Pollination — Fruit — Geographical — Key  to  Chief 

Fruit-bearing  Species  of  Vaccinium 545-547 

Gaylussacia  (Huckleberry,  Tangleberry,  Dangleberry) — 
Description — Geographical — Key  to  North  American  Species 

of  Gaylussacia 547 

Cranberries — Vaccinium    macrocarpon — Types — Vaccinium 

oxycoccus,  Vaccinium  vitis-idaea 548-550 

Huckleberries  and  Blueberries 550 

References 550 

CHAPTER  XXXVL— Oleace^  (Olive  Family). 

Family  Description — Geographical,  and  Economic  Impor- 
tance  551 

Olea  europoea  (Olive) — Description — Seed  Germination — 
Propagation — Uses 551-553 

CHAPTER  XXXVII.— CoNVOLVULACE^  (Morning  Glory  Family). 
Habit — ^Leaves — Inflorescence  and   Flowers — Fruit — Key  to 

Important  Genera 554-555 

Ipomoea  batatas  (Sweet  Potato) — Roots  and  Stems — ^Leaves— 
Inflorescence  and  Flowers — Geographical,  and  Environmental 
Relations — Closely  Related  Species — Types  and  Varieties — 
Leaf  Shape  as  a  Basis  of  Classification — Uses — References.  .555-558 

CHAPTER  XXXVIII.— SoLANACEiE  (Potato  Family). 

Habit  of  Plants — Leaves — Inflorescence  and  Flowers — Fruit 

— Key  to  Important  Genera 559-560 

Solanum — Habit — ^Leaves — Inflorescence,      and      Flowers — 

Fruit — Geographical — Key  to  Important  Species  of  Solanum.. 560-561 


XVm  CONTENTS 

Solanum  tuberosum  (Potato) — Habit — Roots — Stems — 
Leaves — Flower — Opening  of  Flower  and  Pollination — Fruit 
—Seed — Germination — Development  of  the  Seedling — Tubers 
from  Seedlings — Tuberization — Fungus  Theory  of  Tuberiza- 
tion — History — Varieties — Tuber  Morphology — Periderm  or 
Skin — Vascular  Ring — P arenchym a — Cortex — Medulla  — 
Shape — Color — Eyes — Germination  or  Sprouting  of  Tuber 
— Physical  Composition  of  Potatoes- — Chemical  Composition 
of  Potatoes — Starch  and  Sugar — "Mealiness" — Quality  of 
Potatoes — Degree  of  Maturity  and  Quality— Degeneracy 
of  the  Potato — Environmental  Relations — Uses  of  Potatoes — 

Production  of  Potatoes 561-585 

Solanum  melongena  (Eggplant,  Guinea  Squash) — Description 

— Types  and  Varieties 585-587 

Lycopersicon  (Tomato) — Habit  of  Growth,  and  Stems — Roots 
— Leaves— Inflorescence  and  Flowers — Pollination,  Fertiliza- 
tion, and  Development  of  the  Fruit — Parthenocarpy — Ab- 
normal Tomatoes — The  Mature  Fruit — Geographical — Im- 
portant Species  and  Varieties— Key  to  Types  of  Cultivated 

Tomatoes— Closely  Related  Forms — History — Uses 587-592 

(Capsicum  annuum  (Peppers) — Description — Geographical — 
Other  Species — Types — Key  to  Botanical  Varieties  of  Capsi- 
cum  annuum — Composition — Uses 592-596 

Nicotiana  (Tobacco) — Habit — ^Leaves — Inflorescence  and 
Flowers — Fruit — Geographical    Distribution    and    Economic 

Importance 596-597 

Nicotiana  tabacum  (Tobacco) — Habit,  Roots,  Stems — ^Leaves 
— Inflorescence  and  Flowers — Pollination  and  Fertilization  — 
Fruit — Geographical— Closely  Related  Species — Types  and 
Varieties— Composition — Curing  Tobacco — The  Tobacco  In- 
dustry—References  597-605 

CHAPTER  XXXIX.— CucuEBiTACE^  (Gotod  Family). 

Habit — Stems  and  Leaves — Flowers — Fruit — Germination  of 

Cucurbit  Seeds — Key  to  Principal  Genera 606-610 

Cucurbita  (Squash,  Pumpkin,  Gourd;  —Stems,  Leaves, 
Flowers — Pollination     and     Fertilization — Mature     Fruit — 

Geographical — Key  to  Important  Species  of  Cururbita 610-612 

Cucurbita  pepo — Description — Origin — Types  and  Varieties .  613 

Cucurbita  maxima — Description — T3T)es  and  Varieties 614 

Cucurbita  moschata — Description — Types 615 

Cucumis     (Muskmelon,     Cantaloupe,     Cucumber) —Stems, 
Leaves,   Flowers — Pollination — Geographical — Key  to     Prin- 
cipal Species 615-617 


CONTENTS  XIX 

Cucumis  melo  (Muskmelon,  Cantaloupe,  Melons) — Descrip- 
tion— Botanical  Varieties  of  Cucumis  melo 618-620 

Cucumis  sativus  (Cucumber) — Description — Geographical — 

— Closely  Related  Forms — Types — Pickles 620-622 

Cucumis  anguria — Description 622 

Citrullus    (Watermelon,    Citron,    Colocynth) — Description — 

Geographical 622-623 

Citrullus  vulgaris  (Watermelon,  Citron) — Description — Geo- 
graphical— Types  and  Varieties 622-624 

References 624 

CHAPTER  XL.— Composite  (Thistle  Family). 

Habit — Leaves — Inflorescence — Flowers — Key  to  Important 

Genera 625-628 

Lactuca  sativa  (Garden  Lettuce) — Description — Origin,  and 
Geographical — Types  of  Lettuce — Key  to  Types  of  Lettuce.  .  629-633 
Tragopogon  porrifolius  (Salsify  or  "Oyster  Plant") — Descrip- 
tion— Geographical,  and  Closely  Related  Species — Uses 633-635 

Cichorium  (Chicory  or  Succory,  and  Endive) — Description — 

Geographical 635 

Cichorium  intybus  (Chicory  or  Succory)— Description — Uses, 

and  Varieties 636 

Cichorium      endiva       (Endive) — Description — Geographical 

Distribution,  and  Economic  Uses 636-638 

Helianthus  tuberosus  (Jerusalem  Artichoke) — Description — 

Geographical — Closely  Related  Species — Uses 639 

References 639 

Glossary 641-65 1 

Index 653  . 


BOTANY  OF  CROP  PLANTS 


PART  I 

CHAPTER  I 
THE  SEED  PLANT  BODY 

The  seed  plant  body,  like  the  human  body,  is  made  up  of 
a  number  of  separate  parts  or  members.  In  the  lowest  plant 
group,  the  Thallophytes  (thallus  plants),  including  algae 
(pond  scums,  sea  weeds,  etc.),  and  fungi  (molds,  mildews, 
mushrooms,  etc.),  the  plant  body  is  relatively  simple;  it  is 
not  composed  of  distinct  members,  such  as  leaves,  stems, 
roots  and  flowers.  Such  a  simple,  undifferentiated  plant 
body  is  called  a  thallus.  Between  the  typical  thallus  of  algae 
and  fungi  on  the  one  hand,  and  the  highly  complex  and  well- 
differentiated  body  of  seed  plants  on  the  other,  there  are 
many  intermediate  forms,  as  for  example,  among  the  liver- 
worts (Hepaticae). 

Principal  Parts  of  Seed  Plant  Body. — The  parts  of  the 
plant  body  may  be  classified  according  to  the  work  they  do, 
into  two  groups:  (i)  those  that  carry  on  vegetative  activity; 
and  (2)  those  that  carry  on  reproductive  activity.  In  seed 
plants,  the  stems,  leaves  and  roots  are  chiefly  concerned  with 
maintaining  the  life  of  the  individual  plant,  that  is,  carrying 
on  the  vegetative  (nutritive)  functions,  such  as  absorption  of 
materials  from  the  soil,  manufacture  of  foods,  respiration, 


2  BOTANY   OF  CROP  PLANTS 

transpiration,  etc.,  while  the  flowers  which  produce  seeds, 
carry  on,  for  the  most  part,  the  reproductive  activities,  and 
thus  preserve  the  life  of  the  race.  However,  we  know  that 
many  seed  plants,  such  as  potatoes,  asparagus,  cane  fruits, 
strawberries,  and  others  may  be  propagated  by  using  vege- 
tative parts  of  the  plants. 

The  above  classification  has  a  physiological  basis. 

We  may  also  divide  the  seed  plant  body  into  two  systems 
on  a  structural  basis,  as  follows: 

1.  Shoot  system,  including  stems,  leaves,  flowers,  fruit  and 
seed.  The  stems  may  be  in  the  air  {aerial)  or  underground; 
the  leaves  may  be  ordinary  foliage  leaves,  floral  leaves  (flower 
parts),  or  scale  leaves. 

2.  Root  system,  which  may  be  in  the  soil,  the  water  or  air. 
The  roots,  stems,  leaves  and  flowers  are  not  always  typical, 

but  may  be  modified  or  disguised,  in  some  cases  to  such  an 
extent  as  to  be  scarcely  recognizable.  For  example,  the 
tendril  of  the  sweet  pea  is  a  leaf  part,  morphologically;  the 
potato  tuber,  a  modified  stem;  the  sweet  potato,  a  modified 
root. 

Size  and  Form  of  the  Seed  Plant  Body. — There  is  a  re- 
markable variety  of  forms  and  sizes  of  seed  plants  in  the 
world.  The  duckweeds  are  very  small,  simple  seed  plants 
floating  upon  the  surface  of  ponds.  They  are  without  leaves 
or  with  only  very  simple  ones,  they  bear  one  or  more  rootlets, 
and  extremely  small  flowers  which  usually  consist  of  a  single 
stamen  or  a  single  pistil.  At  the  other  extreme  are  the  Giant 
Sequoias  of  California;  one  individual,  the  General  Sherman 
''big  tree,"  measures  279.9  feet  in  height  and  102.8  feet  about 
the  base. 

We  commonly  make  a  distinction  between  trees,  shrubs  and 
herbs — plants  which  differ  much  in  form  and  habit.  Trees 
and  shrubs  are  woody,  while  herbs  possess  iess  woody  tissue 


THE   SEED   PLANT  BODY  3 

and,  consequently,  are  more  soft  and  tender.  The  tree  has 
a  main  trunk  giving  off  branches  at  varying  distances  from 
the  ground.  The  shrub  may  have  a  small  main  stem,  but 
the  shoots  that  arise  at  its  base  are  equal  to  it  in  size.  We 
note  differences  in  the  shapes  of  plants.  Contrast  the  apple 
tree  with  its  oval  shape  with  the  cone  shape  of  the  pine  or 
spruce.  Observe  the  general  columnar  form  of  the  corn 
plant,  and  note  how  different  it  is  from  the  broadly  oval  form 
of  a  vigorous  alfalfa  clump.  Again,  we  see  that  while  most 
plants  are  erect,  a  number,  like  the  strawberry  and  melons, 
are  prostrate  on  the  ground.  Others,  like  the  grape,  are 
climbing,  and  gain  mechanical  support  from  other  objects. 


CHAPTER  II 

FUNDAMENTAL    INTERNAL    STRUCTURE  OF  PLANT 
BODY 

Organs  and  Tissues. — We  have  said  that  the  seed  plant 
body  is  composed  of  a  number  of  members:  roots,  stems, 
leaves,  and  flowers,  bearing  the  fruit  and  seed.  We  may  say 
that  the  plant  body  is  composed  of  a  number  of  organs,  that 
is,  well-defined  parts  that  perform  some  definite  function  or 
functions.  For  example,  those  parts  of  the  plant  concerned 
with  absorption  we  call  absorptive  organs,  those  that  carry  on 
reproduction,  reproductive  organs,  and  so  on.  The  roots  are 
the  chief  absorptive  organs  of  all  common  seed  plants,  and 
the  stamens  and  pistils  of  the  flower  the  reproductive  organs. 
Now,  if  we  study  microscopically  the  structure  of  organs, 
they  are  seen  to  be  made  up  of  one  or  more  different  groups  of 
cells.  Each  distinct  group  of  cells  within  the  organ  that  has 
a  common  origin  and  a  common  role  to  perform,  is  desig- 
nated a  tissue.  For  example,  the  pistil  (a  reproductive  organ 
of  a  flower)  is  composed  of  several  different  tissues  such  as 
parenchyma  tissue,  conductive  tissue,  and  epidermal  tissue. 
Still  deeper  analysis  of  tissues  shows  all  to  be  made  up  of 
small  microscopic  units — the  cells. 

The  Plant  Cell. — Discovery  of  the  Cell. — The  discovery  of 
the  plant  cell  is  attributed  to  Robert  Hooke,  an  Enghsh  lens 
manufacturer.  In  his  microscopic  study  of  thin  sections  of 
ordinary  bottle  cork,  in  1667,  he  observed  the  cork  tissue  to 
be  composed  of  very  small  compartments,  very  much  alike 
in  size  and  shape,  and  fitting  closely  together.     It  happens 

4 


FUNDAMENTAL   INTERNAL   STRUCTURE    OF   PLANT  BODY      5 

that  the  separate  units  making  up  the  cork  tissue  resemble 
the  cells  of  a  honeycomb,  and  hence  Hooke  gave  the  name 
"  cell "  to  the  units  of  cork  tissue.  Although  an  inappropriate 
name,  in  that  the  majority  of  plant  cells  have  no  resemblance 
to  those  of  a  honeycomb,  the  name  still  clings  to  botanical 
terminology.  Hooke's  discovery,  although  an  epoch  in  the 
history  of  biology,  was  to  be  followed  by  others  of  far  greater 
importance  in  that  they  tell  us  of  the  real  nature  of  the  cell, 
its  marvelous  inner  structure,  and  most  wonderful  activities. 

The  Cell  as  a  Unit  of  Structure. — Just  as  a  brick  house  is 
made  up  of  individual  units,  the  bricks,  so  is  a  plant  composed 
of  individual  units,  the  cells.  A  plant  is  made  up  of  cells  and 
the  products  of  cells,  and  nothing  else.  The  wood,  the  root, 
the  flower  parts,  the  leaf,  are  made  up  of  cells  and  cell  prod- 
ucts. This  must  not  be  understood  to  mean  that  all  parts 
of  a  plant  are  alive;  but  the  non-Hving  portions  are  products 
of  the  living  material  within  the  cell. 

The  Cell  as  a  Unit  of  Plant  Activity. — The  activities  of  a 
plant  take  place  within  the  cells,  for  it  is  within  them  that 
we  find  the  living  material— protoplasm.  Some  of  the  sim- 
plest plants  are  unicellular,  that  is,  one-celled.  In  such  a 
case,  the  individual  plant  is  simply  one  cell.  That  one  cell, 
that  individual,  is  capable  of  carrying  on  all  the  processes — 
absorption,  respiration,  digestion,  assimilation,  reproduction, 
etc. — upon  which  its  life  and  the  life  of  the  race  to  which 
that  plant  belongs  are  dependent.  Somewhat  higher  in  the 
scale  of  plant  life,  we  find  some  plants,  algae,  for  example, 
composed  of  a  number  of  cells,  several  hundred,  for  instance. 
In  this  case,  the  individual  plant  is  multicellular,  and  yet,  in 
this  plant,  each  cell  is  a  unit  of  activity,  and  each  carries  on 
its  activities  quite  independently  of  the  others  to  which  it  is 
united,  as  is  evidenced  by  the  ability  of  the  individual  cells 
to  Uve  and  reproduce  when  separated  from  its  neighbors.     In 


6  BOTANY   OF   CROP   PLANTS 

the  higher  seed  plants,  there  are  many  different  sorts  of  cells, 
both  in  structure  and  function,  and  the  different  cells  are 
more  dependent  one  upon  another  than  are  the  cells  that 
make  up  the  simple  algal  filament.  Yet,  even  in  the  seed 
plant,  each  cell  is  a  unit  of  activity,  and  each  is  carrying  on 
its  functions  more  or  less  independently  of  its  neighbors. 
The  physiological  unit  of  the  plant  is  the  cell. 

The  Structure  of  the  Plant  Cell  (Fig.  i).— It  must  be 
understood  at  the  beginning  that  plant  cells  vary  a  good  deal 
in  size  and  shape.  However,  the  fundamental  structure  of 
all  plant  cells  is  much  the  same.  The  plant  cell  consists  of 
a  living  mass  {protoplast)  of  protoplasm  enclosed  in  a  non- 
living cell  wall.  The  wall  is  manufactured  by  the  protoplast, 
and  serves  as  a  protection  to  it.  If  we  examine  the  proto- 
plast, we  see  that  it  is  composed  of  rather  definite  parts. 
There  is  an  outer,  thin,  and  transparent  living  membrane 
about  the  protoplast,  whichis  only  made  manifest  by  treating 
the  cell  in  a  special  manner.  This  membrane  is  known  as  the 
protoplasmic  membrane,  ectoplasm  or  hyaloplasm.  It  is  all- 
important  in  the  intake  and  outgo  of  substances.  If  a  plant 
tissue  is  immersed  in  a  sugar  or  salt  solution  which  has  a 
greater  concentration  than  the  cell  sap,  water  is  drawn  from 
the  protoplast  of  each  cell  through  the  protoplasmic  mem- 
brane, and  the  protoplast  shrinks,  thus  pulling  the  membrane 
away  from  the  cell  wall  and  making  it  visible  microscopic- 
ally. Imbedded  within  the  body  of  the  protoplast  there  is 
a  darker  and  denser  mass  of  protoplasm,  the  nucleus,  sur- 
rounded by  its  own  living  nuclear  membrane.  It  may  con- 
tain one  to  several  small,  darker  bodies,  the  nucleoli.  The 
protoplasm  outside  the  nucleus  is  designated  the  cytoplasm. 
Hence  we  see  that  the  protoplast  is  made  up  of  three  main 
parts:  protoplasmic  membrane,  cytoplasm  and  nucleus.  The 
protoplasm  has  spaces  within  it,  which  are  filled  with  cell  sap. 


FUNDAMENTAL   INTERNAL   STRUCTURE    OF   PLANT  BODY      7 

These  spaces  are  called  vacuoles.  However,  one  must  not 
think  of  the  cell-sap  spaces  in  the  protoplasm  as  vacuums,  as 
the  rather  inappropriate  name  "vacuole"  may  suggest. 
Vacuoles  are  numerous  and  small  in  the  young  cells,  but  as 


Fig.  I. — A,  young  cells  from  onion  root  tip;  d.,  protoplasmic  membrane;  c, 
cytoplasm;  a,  nuclear  membrane;  d,  nucleolus;  e,  plastids  (black  dots).  B, 
older  cells  farther  back  from  the  root  tip;  /,  vacuole;  note  that  the  cells  have 
enlarged.  C,  epidermal  cell  of  Tradescantia  zebrina;  in  its  natural  condition 
of  the  right,  and,  on  the  left  with  the  protoplast  drawn  from  the  cell  wall  as 
the  result  of  immersing  the  cell  in  a  solution  the  concentration  of  which  is 
greater  than  that  of  the  cell  sap.  .  This  phenomenon  is  called  plasmolysis.  g, 
contains  the  plasmolyzing  solution.     (After  Stevens.) 


the  cell  ages,  they  coalesce  to  form  larger  spaces.  In  some 
instances,  there  is  one  large  central  vacuole,  while  the  cyto- 
plasm and  nucleus  are  squeezed  out  close  to  the  cell  wall. 


Plant  cell 


8  BOTANY   OF    CROP   PLANTS 

All  vacuoles  are  bordered  by  a  protoplasmic  membrane,  simi- 
lar to  the  ectoplasm. 

Suspended  within  the  cytoplasm  are  specialized  living 
bodies,  the  plasHds,  also  numerous  granules,  which  may  be 
of  living  material  and  insoluble  food  particles,  such  as  starch 
or  protein.  The  cytoplasm  may  hold  insoluble  crystals  of 
salts,  chiefly  calcium  oxalate.  Let  us  arrange  the  parts  of 
cell  thus  far  described  in  outline  form  as  follows: 

Cell  wall  (non-living) 

f  Protoplasmic  membrane  (living) 

I  Nucleus  (living),  containing  one  or  more  nucleoli 

Protoplast.    \  I  plastids  (living) 

I   „  ^     ,  j  granules  (living   or  non-living) 

Cytoplasm,   i  ^      ,  ,    /        ,.  •     n 
[  I  crystals  (non-livmg) 

[  vacuoles,  containing  cell  sap. 

The  Cell  Wall.— The  cell  wall  is  a  product  of  the  proto- 
plast. When  young  it  is  almost  pure  cellulose.  As  the 
cell  grows  older,  its  wall  may  thicken  and  become  denser, 
and  have  added  to  it  certain  substances  such  as  lignin,  su- 
berin,  cutin  and  pectin  which  give  it  different  physical 
and  chemical  qualities. 

Plastids. — These  are  specialized  masses  of  protoplasm 
suspended  within  the  cytoplasm.  They  vary  in  size  and 
form.  There  are  three  sorts  of  plastids  based  upon  their 
color:  (i)  leucoplastids,  colorless;  (2)  chloroplastids,  green; 
and  (3)  chromoplastids,  yellow,  orange  or  red. 

Nucleus. — All  typical  cells  have  a  definite  nucleus.  It 
is  wrong  to  regard  the  nucleus  as  the  "seat  of  life"  of  the 
cell,  for  other  portions  of  the  cell  are  all-important,  but  it  is  a 
most  essential  part  of  the  cell.  If  the  nucleus  is  separated 
from  the  cytoplasm  by  artificial  means,  the  cell  dies.  Its 
presence  is  needed,  it  seems,  to  stimulate  respiratory  activity. 
Moreover,  reproduction  of  the  cell — its  division  to  form  two 


FUNDAMENTAL   INTERNAL    STRUCTURE    OF   PLANT  BODY    9 

cells — involves  definite  nuclear  changes,  which  has  led  to 
the  opinion  that  hereditary  characteristics  are  carried  by 
nuclear  matter.  The  structure  of  the  nucleus  is  indeed 
complex,  and  there  is  a  wonderful  chain  of  changes  that 
it  goes  through  at  the  time  of  cell  division. 

Protoplasm. — In  1840,  Hugo  von  Mohl  drew  attention  to 
the  fact  that  the  slimy  substance  in  the  plant  cell  was 
responsible  for  its  life,  and  that  as  soon  as  it  was  removed, 
the  cell  no  longer  had  the  properties  of  livingness.  The 
name  protoplasm  was  applied  to  the  living  portion  of  the 
plant  cell.  Somewhat  later,  1850,  Ferdinand  Cohn,  gave 
positive  evidence  of  the  identity  of  the  living  material 
(protoplasm)  in  plant  cells,  and  of  the  living  material  (so- 
called  "sarcode")  in  animal  cells. 

If  we  examine  a  small  bit  of  protoplasm  under  the  micro- 
scope we  see  that  it  is  a  semi-transparent,  jelly-Uke,  rather 
granular  substance,  resembling  very  much  the  white  of  an 
egg.     It  feels  slimy. 

Protoplasm  is  a  very  complex  chemical  substance.  Al- 
though no  element  has  ever  been  found  in  protoplasm  that 
is  not  also  found  in  the  common  substances  in  the  world 
about  us,  the  exact  arrangement  and  proportions  of  these 
elements  has  not  been  ascertained,  except  in  a  general  way. 
It  is  quite  clearly  established  that  protoplasm  is  a  proteid, 
of  complex  nature,  with  water  as  a  solvent.  Proteids  form 
about  one-half  or  two-thirds  of  the  dry  substance  of  pro- 
toplasm. The  remainder  is  fat,  sugar,  and  other  carbohy- 
drates, organic  acids,  organic  bases,  and  some  mineral 
substances. 


CHAPTER  III 
ROOTS 

Development  of  Root  Systems. — The  root  system  of  a 
plant  is  the  entire  collection  of  roots.  Let  us  trace  out  the 
development  of  different  root  systems,  starting  with  the 
seed.  If  we  examine  soaked  grains  of  wheat,  or  bean  seeds, 
or  beet  seeds,  we  observe  that  there  is  a  young  root  already 
formed  within  the  seed.  Three  germinating  stages  in  wheat 
are  shown  in  Fig.  2.  The  one  principal  root  or  primary 
root  we  see  in  the  grain  is  the  first  to  appear.  It  breaks 
through  the  root  sheath  (coleorhiza)  which  remains  as  a 
collar  about  the  root  where  it  breaks  through  the  grain  coat. 
Very  soon  two  lateral  roots  appear;  hence  the  primary  root 
system  or  temporary  root  system  consists  of  a  whorl  of  three 
roots.  Since  these  three  roots  were  in  the  seed  in  the 
embryonic  condition  they  are  called  seminal  (seed)  roots. 
The  secondary  roots  appear  in  whorls  at  the  joints  on  the 
stems  some  distance  above  the  three  temporary  roots.  The 
first  whorl  of  permanent  roots  in  wheat  is  generally  about  i 
inch  below  the  soil  surface,  no  matter  at  what  depth  ;the 
grain  was  planted  (Fig.  3).  One  whorl  of  roots  after 
another  is  formed  above  the  first  one,  and  as  a  result  there  is 
built  up  a  fine  network  of  roots,  with  their  branches.  A  root 
system  such  as  described  in  wheat  is  called  a  fibrous  root 
system. 

We  spoke  above  of  the  three  seminal  or  seed  roots,  and  the 
development  of  whorls  of  roots  from  the  nodes  above  as 
shown  in  Fig.  3.     Roots  not  arising  from  the  seed  or  as 


ROOTS  II 

branches  of  seed  roots,  but  from  stems  or  leaves,  are  called 
adventitious  roots.  Hence  the  fibrous  root  system  of  wheat, 
and  of  all  the  other  cereals  and  grasses,  is  in  reality  composed 
of    roots    that    develop    adventitiously.     Adventitious    root 


coleophle 


Fig.   2. — Three  germinating  stages  in  wheat. 


systems  may  appear  under  a  variety  of  conditions.  When 
young  onion  "sets"  are  placed  in  the  ground,  a  set  of  roots 
(adventitious  roots)  appears  at  their  bases.  If  young  one- 
year-old  twigs  or  stems  (cuttings)  of  apple,  raspberry,  willow, 
geranium,  carnation,  chrysanthemum,  rose,  or  of  many  other 
economic  plants  are  placed  in  damp  soil  or  sand,  adventi- 


BOTANY   OF   CROP   PLANTS 


tious  roots  will  appear  at  the  cut  surface,  and  by  develop- 
ment, form  the  characteristic  root  system  of  the  plant.    Some 


ground  line 


Fig.  3. — In  spite  of  the  fact  that  the  grain  of  wheat  was  planted  at  too  great  a 
depth,  the  permanent  roots  were  formed  at  about  i  inch  below  the  soil  surface. 


leaves  will  even  develop  adventitious  roots  from    cut  or 
wounded  leaf  veins.    This  is  true  of  such  leaves  as  begonia, 


ROOTS 


13 


gloxinias,  and  bryophyllum.  In  the  black-cap  raspberry 
and  in  dewberries,  a  shoot  (stem)  may  bend  over  by  its  own 
weight,  and  where  it  strikes  the  ground,  develop  adventi- 
tious roots,  and  thus  secure  a  foothold.  When  once  the 
tip  has  rooted  well,  the  stem   may  be  cut  loose  from  the 


GROUND 


L.I  NE 


.\::;\ 


Hcf-- 


Fig.   .\. — Tap-root  system  of  youny^  sugar  beet.      (Maxsou.) 


parent  stem  and  such  rooted  ti[).s  used  as  "sets."  Straw- 
berries produce  slender  stems,  called  runners.  Adventitious 
roots  may  be  produced  at  the  nodes. 

A  very  different  sort  of  root  system  develo[)s  in  such  plants 


14  BOTANY  OF  CROP  PLANTS 

as  the  beet,  radish,  turnip,  parsnip  and  carrot.  In  the  germi- 
nation of  the  beet  seed,  for  example,  the  primary  root  pushes 
out,  takes  a  straight  downward  course,  and  gives  off  a  few 
lateral  roots.  Hence,  the  primary  root  system  of  the  beet 
consists  of  one  main  root  extending  downward,  with  a  few 
fme  laterals.  Adventitious  roots  do  not  arise,  as  in  wheat, 
nor  does  the  primary  root  system  die,  as  it  does  in  wheat, 
but  the  main  tap  root  of  the  young  plant  continues  to  elongate, 
and  to  give  off  lateral  roots  and  rootlets  (Fig.  4).  The 
"beet"  itself  is  for  the  most  part  an  enlarged  tap  root.  The 
tap  root  of  the  sugar  beet  may  reach  a  depth  of  4  feet,  and 
often  6  or  7  feet.  The  upper  laterals  are  the  largest  of  the 
branch  roots  and  extend  farthest  in  the  soil,  spreading  almost 
horizontally  2  to  3  feet.  The  lower  laterals  are  more  vertical 
and  those  near  the  very  tip  are  almost  parallel  with  the  tap 
root.  A  root  system  such  as  possessed  by  the  beet,  radish, 
turnip,  parsnip,  carrot,  dandehon,  red  clover,  and  many 
other  plants  is  called  a  tap-root  system. 

The  Work  of  Roots. — A  root  system  absorbs,  anchors,  and 
serves  as  storage  organ.  The  small,  young,  tender  roots,  with 
their  root  hairs,  are  largely  absorption  roots,  but  as  the  plant 
gets  older,  new  absorptive  roots  are  continually  being  formed, 
while  the  older  ones  become  thick  and  woody  and  serve  mainly 
as  anchorage  organs.  Familiar  storage  roots  are  those  of 
the  beet,  carrot,  turnip,  parsnip,  sweet  potato,  and  dande- 
lion. The  food  material  stored  up  by  such  plants  for  their 
own  use  furnishes  a  large  proportion  of  the  food  supply  of 
man.  Irish  potatoes  (tubers)  are  not  roots,  but  stems,  and 
hence  their  discussion  will  be  reserved  for  the  proper  section 
in  the  book. 

Effect  of  Environment  upon  Character  of  Root  System.— 
It  is  noted,  when  roots  make  a  vigorous  growth,  as  they  will 
under  favorable  soil  conditions,  that  there  is  a  very  extensive 


ROOTS 


15 


,plerO),-Ti. 


endodermis 


perl6/em 
Aerwaloqen 


system  of  rootlets  developed.  Corn  is  found  to  have  a  large 
part  of  its  lateral  root  system  in  the  surface  layers  when  the 
soil  is  poor.  The  general  form  of  a  root  system  may  be 
changed  by  transplanting.  As  a  result  of  the  necessary  in- 
jury accompanying  this  process,  there  is  developed  a  compact 
root  system.  Desert  plants  usually  have  an  extensive  root 
system,  reaching  to  considerable  depths,  Swamp  plants, 
even  trees,  develop  a  spreading,  and  comparatively  shallow 
root  system.  The  method  and  amount  of  watering  affect 
the  general  shape  of  the 
root  system.  Fruit  trees, 
for  example,  send  their 
roots  into  the  deeper  soil 
layers  if  the  surface  layers 
are  dry,  but  if  the  ground 
water  level  is  close  to  the 
soil  surface  the  root  sys- 
tem will  be  more  super- 
ficial. The  character  of 
the  root  system  is  often 
an  index  of  soil  conditions. 
General  Characteristics 
of  Roots. — It  will  be  re- 
called that  the  seed  plant 
body  possesses  a  number 
of  members,  each  with 
more  or  less  distinctive 
characters.  .  Roots  have  characteristics  which  stand  out 
in  quite  marked  contrast  to  those  of  other  plant  members. 
Roots  do  not  give  off  their  branches  in  a  regular  order, 
as  stems  do.  They  do  not  bear  buds,  except  in  very  rare 
cases.  Roots  usually  bear  a  root  cap  (Fig.  5)  which  pro- 
tects the  growing  point,  while  the  growing  point  in  stems 


region  of  ^ 

ariatesir 
iellmu/tif^ica 


Fig.  5. — Median  lengthwise  section  of 
the  apex  of  a  root  of  barley.  (After 
Slrasburger.) 


l6  BOTANY   OF   CROP   PLANTS 

is  either  naked  or  surrounded  by  modified  leaves  (bud 
scales).  There  are  other  characters  which  will  be  mentioned 
further  on. 

Classification  of  Roots  Based  upon  Their  Medium  of 
Growth.^ — The  medium  of  growth  of  most  roots  is  soil.  Such 
roots  may  be  called  soil  roots.  It  is  customary  for  us  to 
think  of  the  root  system  of  a  plant  as  growing  in  the  soil, 
just  as  we  associate  the  shoot  system  with  the  air  above 
ground.  However,  not  all  roots  live  in  the  soil,  and  not  all 
shoots  hve  in  the  air.  There  are  water  roots,  and  air  roots, 
as  well  as  the  ordinary  sort,  soil  roots.  Water  roots  occur 
in  such  floating  plants  as  the  duckweeds,  water  hyacinth 
{Eichhornia  speciosa).  Water  roots  produce  but  a  few 
branches.  They  possess  no  root  hairs;  absorption  takes  place 
through  any  cells  on  the  surface.  Air  roots  occur  in  many 
plants,  such  as  corn  (Fig.  56,  B),  Virginia  creeper,  tropical 
orchids,  the  banyan  and  other  species  of  Ficus.  Air  roots  are 
well  shown  in  corn.  In  addition  to  the  ordinary  underground 
(soil)  roots,  corn  develops  aerial  (air)  roots,  the  so-called  prop 
or  brace  roots  (Fig.  56,  B).  These  arise  at  successive  levels 
above  the  surface,  extending  obliquely  downward.  As  aerial 
roots,  they  are  unbranched,  but  they  branch  profusely  when 
they  strike  the  soil.  They  have  the  role  of  absorption,  then, 
as  well  as  anchorage.  In  the  banyan,  for  example,  the  air 
roots  are  often  very  large,  and  arise  from  branches  far  above 
the  ground.  They  grow  downward,  and  when  they  strike 
the  ground,  become  firmly  attached,  and  act  as  a  support 
or  prop  to  the  heavy  branches. 

Hence,  we  learn  that  not  all  roots  have  soil  as  their  medium 
of  growth,  but  that  air  and  water  may  be  the  media  for  some. 

Structure  of  Roots. — ^Let  us  cut  a  median  (middle)  length- 
wise section  of  a  young  root.  It  will  appear  as  in  Fig.  5. 
We  shall  see  then  that  the  root  has  a  cap  of  loose  cells  at  the 


ROOTS 


17 


tip.  This  protective  structure  is  called  the  root  cap.  Just 
back  of  the  root  cap  is  the  region  of  greatest  cglljnultiplica- 
tion  (Fig,  5),  composed  of  cells  that  are  actively  growing. 
The  very  tip  of  the  cap  is  continually  sloughing  off,  while 
new  cells  are  being  added  to  it 
just  in  front  of  the  growing  point. 

In  addition  to  the  root  cap  we 
note  that  there  are  three  distinct 
parts  to  the  root,  namely,  (jX. 
dermatogen,  an  outer  layer  or 
layers;  (2)  plerome  (axis);  and  Q}. 
periblem^etween  the  dermatogen 
and  plerome.  The  dermatogen 
becomes  the  epidermis,  the  plerome 
the  stele  or  central  cylinder,  and 
the  periblem  the  cortex.  It  is 
often  possible  to  strip  the  cortex 
and  epidermis  from  the  central 
cylinder,  which  is  composed  of 
tough,  fibrous  tissue.    ' 4^ 

The  cortex  (Fig.  6)  is  composed 
of  large,  thin-walled  cells,  which 
do  not  fit  closely  together,  but 
leave  air  spaces  (inter-cellular 
spaces)  between.  The  innermost 
cortex  layer  is  called  the  endo- 
dermis.  The  outer  cortex  cells 
may  become  prolonged  to  the  side 
to  form  root  hairs.  The  central 
cylinder  or  stele  (Fig.  6)  is  bounded 
by  a  single  layer  of  cells,  the  pericycle,  which  lies  adjacent 
to  the  endodermis.  Within  the  stele  are  found  alternat- 
ing bundles  or  strands.     The  woody,  water-conducting  bun- 


FiG.  6. — Cross-section  of  a 
young  root  of  Phaseolus  mul- 
tiflorus.  A,  pr,  cortex;  m, 
pith;  X,  stele  or  central  cylin- 
der— all  tissue  within  the  peri- 
cycle, inclusive;  g,  primary 
xylem  bundles;  b,  primary 
phloem  bundles.  B,  cross- 
section  of  older  portion  of 
root;  lettered  as  in  ^;  b', 
secondary  phloem.  (After 
Vines.) 


i8 


BOTANY   OF   CROP   PLANTS 


dies  are  called  the  xylem,  the  softer,  food- 
conducting  bundles,  phloem.  The  central 
portion  of  the  stele  is  composed  of  large, 
loosely  fitting  cells,  making  up  the  pith  or 
medulla. 

Side  roots  arise  from  the  outer  edge  of 
^j,  the  stele  (central  cylinder),  and  push  their 
way  through  the  cortex  and  epidermis 
(Fig.  7).  This  method  of  origin  of  side 
branches  is  characteristic  of  roots.  In 
stems  the,  side  branches  arise  from  the  outer 
part  of  the  cortex  (Fig.  15).  Branch  roots 
are  said  to  have  an  endogenous  origin, 
while  branch  shoots  (except  those  in  mono- 
cots)  have  an  exogenous  origin. 

As  the  root  grows  older,  new  xylem  and 
phloem  are  formed,  and  by  and  by,  it  be- 
comes very  tough  and  woody,  serving  as  an 
efficient  anchorage  organ. 

Root  Hairsn^the  Absorbing  Organs  of  a 
Plant. — The  great  problem  of  all  our  com- 
mon plants  is  to  take  in  as  much  water  from 
the  soil  as  they  lose  to  the  air,  i.e.,  to  main- 
tain a  balance  between  water  intake  and 
water  outgo.  We  speak  of  the  roots  as  the 
absorbing  organs  of  the  plant.  In  a  sense 
this  is  true,  but  it  must  be  understood  that 
water  and  soil  solutions  are  not  taken  in  at 
all  points  on  the  surface  of  the  root  system. 
Practically   all   absorbed  substances  enter 


Fig.  7. — Young  root  of  white  lupine  showing  origin 
of  lateral  roots  from  the  stele.     {After  Gager.) 


ROOTS 


19 


the  plant  through  root  hairs,  which  are  found  near  the  tips  of 
the  smallest  rootlets.  In  reality,  the  root  hairs  are  the  ab- 
sorbing organs  of  a  plant.  When  we  pull  up  any  common 
herbaceous  plant,  we  observe,  as  a  rule,  a  large  number  of 
hair-hke  rootlets  as  branches  of  larger  roots.  These  fine 
"hair  roots"  are  sometimes  mistaken  for  root 
hairs.  But,  closer  examination,  in  which  a 
hand  lens  may  be  necessary,  shows  us  that 
these  hair  roots  are  the  bearers  of  root  hairs. 
In  fact,  root  hairs  are  found  only  on  the 
smallest  and  youngest  rootlets. 

Root-hair  Zone. — Root  hairs  do  not  grow 
along  the  full  length  of  a  rootlet,  but  occupy 
a  definite  zone,  designated  the  root-hair  zone. 
This  is  clearly  seen  in  young  seedlings, 
grown  on  moist  filter  paper.  The  root- 
hair  zone  appears  as  a  white  fuzzy  coating. 
The  root  cap  is  free  of  root  hairs.  The 
length  of  the  zone  varies  from  a  few  milli- 
meters to  several  centimeters.  The  root- 
hair  zone  of  seedlings  grown  in  soil  is  plainly 
evident  from  the  mass  of  soil  particles  held 
by  the  root  hairs  (Fig.  8).  Each  root  hair 
in  its  growth  flattens  out  over,  and  some-      ^]°-  8.— Wheat 

°  '  seedling    snowing 

times  partially  surrounds,  the  soil  particles  soU  particles  cUng- 
with  which  it  comes  into  contact,  thereby  nTtethltTh^root 
forming  a  close  connection  with  the  water  cap  is  free  of  root 
and  solutes  that  form  a  thin  film  around 
each  soil  particle  (Fig.  9).  Furthermore,  the  root  hairs 
become  mucilaginous,  and  this,  along  with  their  partial  sur- 
rounding of  particles,  explains  the  presence  of  the  mass  of 
soil  particles  that  clings  to  rootlets  in  the  root-hair  zone. 
Root  hairs  are  short-lived,  persisting  for  only  a  few  days  or 


^1 


BOTANY   OF   CROP   PLANTS 


weeks.  New  hairs  are  constantly  formed  anew  at  the  an- 
terior end  of  the  root-hair  zone,  while  those  at  the  posterior 
end  are  dying.     Root  hairs  do  not  become  roots. 

Structure  of  a  Root  Hair. — The  root  hair  is  a  single  cell. 
It  is  a  simple,  lateral  prolongation  of  a  border  cell  of  the  cor- 
tex (Fig.  9).  It  has  the  shape  of  a  slender  tube  which  may, 
however,  become  greatly  contorted  in  its  growth  between  and 
about  soil  particles.  Root  hairs  vary  in  length  from  a  frac- 
tion of  a  millimeter  to  7  or  8  millimeters.     The  walls  are  thin 


Fig.  9. — Root  hairs.     {After  Gager.) 

and  of  almost  pure  cellulose.  A  thin  layer  of  protoplasm 
may  line  the  walls,  and  the  nucleus  usually  occupies  a  posi- 
tion near  the  apex.  The  central  vacuole  is  large,  and  is  filled 
with  cell  sap.  The  cell  sap  contains  water,  and  various  or- 
ganic and  inorganic  substances  in  solution. 

Effect  of  External  Factors  upon  Development  of  Root 
Hairs. — Most  air  and  water  roots  have  no  root  hairs.  Soil 
roots,  such  as  those  of  conifers,  oaks,  and  others  that  are 
surrounded  by  a  fungus  (mycorrhizal  growth)  possess  no  root 
hairs.  In  the  case  of  ordinary  soil  roots,  root-hair  develop- 
ment is  usually  meager  in  very  wet  soil.  Corn  roots  develop 
root  hairs  in  abundance  in  moist  air,  but  none  at  all  in  water. 
The  absence  of  root  hairs  in  very  wet  soil,  and  in  water,  is 
probably  to  be  attributed  to  poor  oxygen  supply.     In  a 


ROOTS  21 

water-soaked  soil,  the  air  spaces  are  filled  with  water.  Our 
ordinary  crop  plants  require  a  well-aired  soil  in  order  to  de- 
velop root  hairs  in  abundance.  One  of  the  chief  objects  of 
stirring  the  soil  is  to  admit  air  to  the  roots.  Orchard  trees 
have  been  known  to  die  as  a  result  of  the  "puddling"  of  the 
soil.  Trees  are  also  sometimes  killed  by  cattle  tramping  and 
packing  the  ground  about  them,  such  that  the  air  supply  to 
the  roots  is  largely  cut  off.  Root-hair  development  is  often 
inhibited  by  a  concentrated  soil  solution.  High  tempera- 
tures, and  low  temperatures,  are  inimical  to  root-hair  growth. 
Root  hairs  develop  in  the  light  and  dark  about  equally  well, 
providing  there  is  ample  moisture. 

Length  of  Life  of  Roots.— Roots  that  live  but  one  vegeta- 
tive period,  that  is,  one  season,  are  annual.  All  of  our  com- 
mon cereals,  such  as  wheat,  oats,  barley,  rye,  corn,  rice, 
sorghum,  and  also  such  common  crop  plants  as  buckwheat, 
beans,  peas,  tomatoes,  melons,  etc.,  have  annual  roots. 
Biennial  plants  live  two  vegetative  periods.  Common 
biennials  are  beet,  cabbage,  carrot,  and  parsnip.  From  the 
seed  of  beet,  for  example,  there  is  developed  the  first  season 
a  large  fleshy  tap  root,  and  a  short  crown  from  which  the 
leaves  arise.  This  fleshy  structure  ("beet"),  stored  with 
food,  rests  over  the  winter,  and  the  next  growing  period 
sends  up  stout,  branching  stems  to  a  height  of  3  or"  4  feet, 
which  give  rise  to  flowers  and  seed  (Fig.  119).  At  the  end 
of  the  second  season  of  growth,  after  seed  production,  the 
entire  plant  dies.  Under  our  cultural  conditions  winter 
wheat  is  a  biennial.  The  roots  of  trees  and  shrubs  and  some 
herbs  live  from  year  to  year,  increasing  in  size  each  season. 
Such  plants  are  perennial  in  habit.  In  most  cases  the  length 
of  life  of  roots  is  the  same  as  that  of  the  shoot  system.  How- 
ever, underground  perennial  stems,  such  as  are  possessed 
by  quackgrass,  Canada  thistle,  false  Solomon's  seal,  etc., 
may  have  annual  roots. 


CHAPTER  IV 
STEMS 

Development  of  Shoot  System. — When  a  grain  of  wheat 
germinates,  the  primary  root  is  the  first  to  appear.  Very 
soon  two  lateral  roots  make  their  appearance,  forming  a 
primary  root  system  of  three  roots.  Also,  the  young  stem 
(Fig.  i)  elongates,  and  there  is  formed  the  first  shoot 
system  of  the  plant.  Elongation  of  the  stem  continues  by 
growth  at  the  tip,  where  the  cells  are  young  and  active. 

It  is  observed  that  the  stem  is  divided  into  sections  (inter- 
nodes)  (Fig.  25).  The  nodes,  the  enlarged  joints  between 
the  internodes,  give  rise  to  leaves,  and  if  we  follow  the  wheat 
plant  through  its  hfe,  we  observe  that  the  stem  terminates 
in  an  inflorescence  (flower  cluster).  Now,  in  addition  to  the 
one  main  stem  that  arises  as  a  prolongation  of  the  embryonic 
stem  in  the  seed,  branches  arise  from  the  lower  nodes.  These 
branches  arise  in  the  axils  of  the  lowermost  leaves,  in  most 
cereals.  In  cereals,  this  branching  is  known  as  " stooling" 
or  ^^ tillering"  Common  cereals  invariably  produce  a  num- 
ber of  tillers  or  branches  from  the  primary  stem,  and  these 
in  turn  other  tillers  (lateral  branches),  so  that  under  favorable 
conditions  several  dozen  culms  may  result  from  a  single  seed. 
In  the  wheat  plant,  two  or  three  weeks  old,  three  or  four 
buds  (young  stems)  may  be  found,  one  in  the  axil  of  each 
leaf.  Tillering  results  from  the  outgrowth  of  these  lateral 
buds.  Hence,  as  a  result  of  the  elongation  of  the  main 
growing  point,  and  of  the  lateral  growing  points  into  lateral 


STEMS  23 

branches  of  the  primary  stem,  there  is  built  up  a  shoot  sys- 
tem, with  its  leaves  and  flowers. 

Buds. — A  bud  is  an  undeveloped  stem;  it  is  simply  a  young 
shoot.  In  an  ordinary  shoot,  an  apple  or  peach  twig'^for 
example,  the  internodes  are  considerably  elongated.  In 
rapidly  growing  water  sprouts,  internodes  may  be  several 
inches  in  length.  A  bud  is  a  very  short,  young  shoot  in 
which  the  internodes  'are  few  or  are  exceedingly  short. 
That  a  bud  is  a  young,  individual  shoot  in  itself  is  shown 
by  the  fact  that  buds  may  be  removed  from  a  branch 
and  applied  to  the  surface  of  the  growing  tissue  (cambium) 
of  another  branch  (stock)  and  successfully  grown  there.  In 
fact,  bud  grafting  is  a  common  horticultural  practice.  The 
tip  of  the  bud  is  usually  protected  by  a  series  of  overlapping 
scales  (bud  scales),  which  are  in  reality  modified  leaves. 
Naked  buds  are  not  protected  by  scales;  they  are  found  on 
woody  plants  of  the  moist  tropics,  and  are  the  only  sort  on 
herbaceous  plants  the  world  over. 

Classification  of  Buds.^ — Buds  may  be  classified  as  to 
development  into:  (a)  leaf,  (b)  flower,  and  (c)  mixed  buds. 
If  we  open  up  a  leaf  bud,  we  find  a  very  much  shortened  axis 
or  stem  bearing  a  number  of  small  leaves.  As  the  leaf  bud 
is  a  young  shoot,  it  may  as  properly  be  called  a  branch  bud. 
That  is,  it  elongates  into  a  branch  which  bears  leaves.  The 
new  shoot,  just  as  the  old  one  from  which  it  came,  ends  in  a 
bud,  and  in  the  leaf  axils  other  buds  arise.  If  we  open  up  a 
flower  bud,  we  find  one  or  more  young  flowers.  In  plums, 
for  example,  the  number  of  flowers  in  a  bud  varies  from  one 
to  five,  two  and  three  being  the  most  common  numbers 
(Fig.  166).  Mixed  buds  contain  both  flowers  and  leaves. 
The  terminal  buds  at  the  ends  of  the  short  "spurs"  in  the 
apple  are  mixed  buds  (Fig.  153). 

It  is  not  always  possible  to  distinguish  leaf  from  flower 


24  BOTANY  OF  CROP  PLANTS 

buds  by  their  external  appearance.  In  some  cases,  however, 
they  have  a  different  shape.  In  the  apple,  for  example, 
fruit  buds  (here,  really  mixed  buds)  are  rather  thick  and 
rounded,  while  leaf  buds  are  smaller  and  more  pointed. 
In  all  plums,  the  flower  buds  are  lateral,  and  usually  stand 
out  at  an  angle  of  about  30°,  while  leaf  buds  are  more  ap- 
pressed  to  the  stem. 

Buds  may  be  classified  as  to  their  position  on  the  stem  into: 
(a)  terminal,  ih)  lateral  or  axillary,  ic)  accessory  or  super- 
numerary, (d)  adventitious,  and  (e)  dormant. 

Most  stems  end  in  a  bud.  Such  a  terminal  bud  is  almost 
always  a  leaf  bud;  occasionally  it  bears  flowers,  too,  as  in  the 
apple.  The  terminal  bud  is  normally  the  most  vigorous  of 
all  on  the  stem,  as  is  evidenced  by  the  fact  that  it  elongates 
into  a  shoot  which  exceeds  in  length  those  from  the  lateral 
buds.  Lateral  (side)  buds  arise  in  the  leaf  axils.  They  give 
rise  to  side  branches  or  to  flowers.  Accessory  or  supernumer- 
ary buds  are  extra  ones  coming  out  in  the  leaf  axils.  They 
are  best  shown  in  the  maples  and  box  elder.  Adventitious 
buds  arise  out  of  order,  in  unusual  places,  not  in  leaf 
axils  or  at  the  end  of  a  stem.  They  are  usually  stimu- 
lated by  injury.  For  example,  when  a  branch  is  cut  back, 
numerous  adventitious  buds  develop  about  the  edge  of  the 
cut  surface.  Dormant  buds  are  ones  that  have  arisen  in  a 
regular  fashion  in  the  leaf  axil,  but  which,  for  some  reason, 
do  not  develop.  Hence,  they  may  be  grown  over  with  the 
succeeding  layers  of  wood  and  He  buried  within  the  tissue  in 
a  latent  condition.  Such  a  bud  may  be  called  into  activity 
later  in  the  life  of  the  plant  and  come  to  the  surface.  It 
would  appear  to  be  endogenous  in  its  origin,  while  in  reality 
it  is  exogenous.  Irregular  branching  may  result  from  the 
development  of  dormant  buds,  or  as  is  more  commonly  the 
case,  from  the  development  of  adventitious  buds. 


STEMS 


25 


Buds  may  be  classified 
as  to  their  arrangement  on 
the  stem  into :  {a)  alternate, 
(b)  opposite  and  (c)  whorled. 
It  is  well  to  keep  in  mind 
that  bud  arrangement  is 
the  same  as  leaf  arrange- 
ment, for  the  reason  that 
buds  normally  develop  in 
each  leaf  axil.  Further- 
more, as  leaf  buds  develop 
into  shoots,  the  method  of 
branching,  and  hence  the 
form  of  the  plant,  is  largely 
determined  by  the  bud 
arrangement. 

When  one  bud  occurs  at 
each  node,  they  are  said 
to  be  alternate  (Fig.  10). 
When  two  buds  stand  at 
a  node,  they  are  opposite 
(Fig.  103).  When  more 
than  two  buds  stand  at  a 
node  they  are  said  to  be 
whorled. 

Bud  Variation.- — This  is 
a  more  or  less  common  oc- 
currence in  trees  of  all 
varieties.  The  buds  on  an 
apple,  peach,  or  citrus  tree, 
for  example,  differ  from 
each  other  in  important 
respects.    That  this  differ- 


terminal  leaf -bud 


flower-buds 
\sfipule-scar 


llenticels 


latent  hud-- 


one  year' 
old  branch 


■  lateral  leaf  buds 


■  terminal  bud- scar 


flower-bud-scars 


:o. — Cottonwood  twig  two  years 
old.     {After  Longyear.) 


26  BOTANY  OF  CROP  PLANTS 

ence  really  exists  can  be  well  shown  by  removing  branches  or 
buds  and  growing  them  into  independent  plants.  If  we  do 
this  we  will  find  that  the  individuals  from  the  separate  buds 
may  vary  in  such  respects  as  habit  of  growth,  manner  of 
branching,  nature  of  foHage,  form,  color,  texture  and  yield 
of  fruits. 

Nearly  all  our  fruits  are  multiplied  by  bud  propagation 
(asexual  parts)  and  not  by  seed  (sexual  parts) ;  and  many  of 
the  varieties  of  fruits  now  in  cultivation  are  in  reality  bud 
varieties  or  " sports."  A  certain  branch  on  a  tree  is  observed 
to  differ  from  the  rest  in  some  marked  respect;  and  this 
branch  is  taken  off  and  propagated  as  a  new  variety. 

General  Characteristics  of  Steins. — ^Let  us  now  examine  a 
winter  twig  of  the  Cottonwood,  for  example,  that  is  several 
years  old,  such  as  pictured  in  Fig.  lo.  At  the  tip  is  a  large 
terminal  bud.  If  it  is  broken  open,  young  overlapping  leaves 
are  found  within.  It  develops  into  a  leafy  branch.  The 
growth  in  length  of  the  shoot  results  from  the  lengthening 
of  the  internodes  in  the  bud.  Along  the  side  of  the  stem  are 
lateral  buds  at  regular  intervals.  These  may  be  leaf  buds  or 
flower  buds,  as  can  be  positively  determined  by  breaking 
them  open.  Below  each  bud  there  is  a  half-moon-shaped  leaf 
scar.  Hence  we  see  that  leaf  arrangement  is  also  bud  ar- 
rangement. By  examining  the  leaf  scar  with  a  hand  lens 
one  sees  several  small  bundle  scars  on  the  surface.  Bundle 
scars  are  left  by  the  vascular  bundles  that  pass  from  the 
woody  stem  into  the  petiole  (stem)  of  the  leaf.  Inflorescence 
scars  are  large  circular  or  oval  scars  left  by  the  falling  off 
of  flower  clusters.  A  leaf  scar  is  observed  beneath  each 
inflorescence  scar.  The  twig  growth  of  each  year  is  clearly 
distinguished  by  a  ring  of  scars.  When  the  closely  arranged 
bud  scales  of  a  terminal  bud  fall  off  in  the  spring  they  leave 
a  number  of  scars  so  close  together  as  to  make  a  ring.     Hence 


STEMS 


27 


the  limits  of  two  successive  years'  growth  are  marked  by 
bud  scale  scars  of  terminal  buds.  In  this  way  we  may 
determine  the  age  of  a  twig. 

Close  observation  of  the  twig  will  reveal  a  number  of 
whitish  spots  on  the  bark.  These  are  lenticels  (Fig.  11), 
structures  on  the  stem  composed  of  a  mass  of  loosely  fitting 
cells  which  permit  the  diffusion  of  gases  inward  and  outward. 
Except  for  the  lenticels,  the  bark  prevents  the  free  passage 
of  air,  and  also  the  loss  of  water  from  underlying  stem  parts. 


W^sg' 


Fig.  II. — Section  of  the  lenticel  of  elder.  (After  Slrasburger.)  From  A 
Text-book  of  Botany  by  Coulter,  Barnes,  and  Cowles.  Copyright,  by  the 
American  Book  Company,  Publishers. 


How  Does  a  Stem  Grow  in  Length? — A  bud  is  a  young 
shoot.  A  lengthwise  section  of  a  leaf  bud  shows  a  cone- 
shaped  growing  point  (young  stem)  upon  which  is  a  number 
of  young  leaves.  These  leaves  come  off  at  regular  intervals, 
following  identically  the  same  arrangement  as  they  do  in 
the  adult  twig.  The  growing  point,  then,  consists  of  a 
number  of  very  much  shortened  internodes.  Growth  in 
length  of  the  shoot  consists  in  the  elongation  of  these  in- 


28  BOTANY  OF  CROP  PLANTS 

ternodes  by  increase  in  number  and  size  of  cells  that  com- 
pose internode  tissue. 

As  a  rule,  the  number  of  leaves  that  will  be  on  a  twig  is 
already  fixed  in  the  bud.  Seldom  do  new  leaves  originate 
during  the  growing  season.  This  point  is  worthy  of  special 
mention:  When  a  twig  has  made  its  year's  growth,  the 
internodes  do  not  lengthen  thereafter  during  subsequent 
years.  Increase  in  length  of  that  shoot  is  due  to  the  addi- 
tion of  other  "joints"  at  the  end.  The  fixed  length  of 
old  internodes  is  well  proven  by  the  common  observation 
that  nails  driven  into  the  trunk  of  a  tree,  or  a  small  branch, 
are  not  elevated  above  the  ground  as  the  tree  grows.  It  will 
become  grown  over  with  wood,  but  its  height  above  the 
ground  remains  the  same.  A  common  impression  prevails 
that  the  branches  of  a  young  tree  should  be  started  low  to 
the  ground,  so  that  they  will  be  at  about  the  right  elevation 
above  the  ground  when  the  tree  reaches  maturity.  The  sup- 
position here  is  that  the  limbs  are  raised  by  the  growth  of 
the  tree.     This  notion  is  erroneous. 

Classification  of  Stems  Based  upon  Their  Medium  of 
Growth. — The  medium  of  growth  of  most  stems  is  air.  Such 
stems  may  arise  from  the  soil  as  in  nearly  all  of  our  ordinary 
plants,  or  they  may  have  no  attachment  with  the  soil  at  all, 
receiving  mechanical  support  from  other  plants.  The  latter 
are  called  epiphytes.  Tillandsia  usneoides  is  probably  the 
best  epiphyte  among  seed  plants.  It  is  the  .  so-called 
"Spanish  moss."  Many  orchids  of  the  moist  tropics  are 
epiphytic. 

The  entire  shoot  system  of  some  plants  is  underground. 
This  is  the  case  in  the  ferns.  Many  plants  produce^both 
aerial  and  subterranean  stems.  For  example,  Canada  thistle 
has  horizontal  underground  stems,  and  from  these  are  sent 
up  aerial  shoots  bearing  foHage  leaves  and  flowers.     Both 


STEMS  29 

underground  and  aerial  stems  are  possessed  by  such  common 
plants  as  Irish  potato,  onion  and  asparagus. 

Water  is  also  a  medium  of  growth  of  stems,  as  is  the  case 
with  such  plants  as  Elodea,  Potamogeton,  water  lilies,  etc. 

"Modified"  Steins. — Undoubtedly,  the  ordinary  cylin- 
drical twig  such  as  is  found  in  trees  and  shrubs  is  the  most 
common  sort  of  stem.  It  is  quite  likely  that  we  think  of  a 
stem  as  a  plant  part  growing  more  or  less  erect,  in  fact,  most 
stems  do  tend  to  grow  erect.  However,  all  stems  are  not  as 
just  described.  As  we  take  a  survey  of  the  plant  kingdom, 
we  discover  many  different  forms  of  stems — stems  that  are 
so  different  from  the  ordinary  sorts  that  they  are  scarcely 
recognizable  as  stems,  and  are  identified  as  such,  only  by 
careful  study  of  their  origin  and  structure.  Among  such 
stems  are  the  following: 

I.  Rootstocks  or  Rhizomes  (Fig.  12). — These  are  under- 
ground, horizontally  elongated  stems.  The  rootstocks  or 
rhizomes  of  Canada  thistle  are  excellent  examples.  They 
bear  reduced,  scale  leaves  at  the  nodes.  Lateral  buds  arise 
in  the  axils  of  these  leaves,  just  as  described  in  the  cotton- 
wood  twig — a  typical  stem.  They  grow  in  length  from  a 
terminal  bud,  which  is  unprotected  by  tough  scales.  Adven- 
titious roots  are  produced  at  the  nodes.  Rootstocks  are 
efficient  organs  in  the  spreading  of  a  plant.  Here  is  a 
method  of  reproduction  other  than  by  seeds.  Usually, 
aerial  stems  from  the  lateral  buds  of  the  rootstock  are  pro- 
duced; they  may  die  back  to  the  ground  each  fall.  The 
plant  lives  over  the  winter  by  means  of  the  rootstocks. 
Hence,  rootstocks  or  rhizome-bearing  plants  are  perennial. 
Many  of  our  worst  weeds  are  perennials  from  a  rootstock. 
We  may  prevent  such  plants  from  going  to  seed,  but  in  spite 
of  this,  and  the  cutting  back  of  the  leafy  shoots,  new  shoots 
are  sent  up  from  the  rootstocks.     Furthermore,  if  the  root- 


30 


BOTANY   OF   CROP   PLANTS 


stocks  are  broken  into  a  number  of  separate  pieces  by 
cultivating  implements,  each  piece  may  develop  adven- 
titious roots,  establish  itself,  and  send  up  leafy  shoots.  Fre- 
quent cultivation  that  has  as  its  aim  the  destruction  of  new 


i/jp—  decurrent 

leaf  base 


xhizome 


Fig.  12. — Portion  of  a  sprouting  potato  tuber. 


shoots  as  soon  as  they  appear,  may  succeed  in  starving  out 
the  rootstock  after  a  time.  The  period  of  time  depends  upon 
the  amount  of  stored  food  material  in  the  structure.  This 
method  of  eradication  is  based  upon  the  knowledge  that  the 


STEMS 


31 


food  of  the  plant  is  manufactured  in  the  chlorophyll-bear- 
ing (green)  cells  above  ground. 

2.  Tubers. — These  are  fleshy,  underground  stems.  The 
best  example  is  common  Irish  potato.  Although  the  potato, 
ordinarily,  would  not  be  considered  a  stem,  still  if  we  follow 
through  its  development,  and  examine  its  structure,  we  are 
convinced  that  it  is  stem  (Fig.  12).  When  we  plant  a 
slice  of  a  potato,  "sprouts"  are  soon  sent  out  from  the 
"eyes."  These  sprouts,  with  their  nodes,  and  internodes, 
and  their  scale  leaves,  are  quite  obviously  horizontal  under- 
ground stems  (rhizomes).  Soon, 
the  tip  of  a  rhizome  begins  to  en- 
large, and  a  potato  is  formed; 
hence,  the  potato  is  seen  to  be  a 
simple  enlargement  of  the  tip  of  an 
underground  stem.  Furthermore, 
examination  of  the  tuber  reveals 
the  presence  of  a  terminal  bud 
("seed  end"  of  the  potato),  and 
lateral  buds  along  the  sides.  The 
buds  are  the  so-called  "eyes." 
In  an  elongated  potato,  we  may 
be  able  to  detect  the  spiral  ar- 
rangement of  the  buds.  Lenticels 
may  also  be  observed  on  the  corky 
layer  (skin)  of  the  bark  of  the 
potato. 

A  section  of  a  tuber  reveals  a  stem  structure.  The  three 
principal  parts  of  an  ordinary  stem  are  bark,  wood  and  pith. 
This  is  shown  in  a  cross-section  of  an  ordinary  twig  (Fig.  13). 
In  the  potato,  these  three  distinct  zones  are  visible,  as  indi- 
cated in  Fig.  236.  Hence,  we  see  that  the  potato  is  in  reality 
a  modified  stem. 


Fig.  13. — Section  of  stem 
showing  a  shedding  leaf;  also 
bark,  wood  and  pith  as  seen 
in  cross  and  longitudinal  sec- 
tions.    (After  Longyear.) 


32 


BOTANY   OF   CROP   PLANTS 


3,  Bulbs. — A  bulb  is  an  underground  stem.  The  common 
onion  is  a  typical  example.  A  median,  lengthwise  section 
(Fig.  14)  of  the  onion  bulb,  shows  a  small,  cone-shaped  stem 

upon  which  are  numerous, 
fleshy  leaves  that  are  over- 
lapping and  quite  rich  in  food 
material.  Here,  too,  there  is 
a  terminal  bud,  and  kteral 
buds  occasionally  in  the  leaf 
axils.  Bulbs  are  vertical 
stems,  thus  differing  from  the 
horizontal  direction  of  growth 
of  rhizomes. 

4.  Corms. — A  corm  is  a 
short,  solid,  vertical,  under- 
ground stem.  It  is  typically 
exempHfied  in  gladiolus. 
Corms  are  usually  flattened 
from  top  to  bottom,  and  bear 
a  cluster  of  thick  fibrous 
roots  at  the  lower  side,  and  a 
tuft  of  leaves  on  the  upper 
side.  Corms  are  storage 
organs. 

5.  Runners  (stolons). — 
These  resemble  rhizomes  in 
that  their  direction  of  growth 
is  horizontal.  In  the  straw- 
berry plant,  the  branches  that  arise  from  the  axils  of  the 
closely  set  leaves  are  called  "runners."  They  are  slender 
stems,  growing  along  the  ground  surface;  they  have  long 
internodes,  and  produce  leaves,  flowers  and  roots  at  the 
nodes.     Runners  are  used  as  a  means  of  propagating  the 


Fig.  14. — Median  lengthwise  section 
of  common  onion  bulb. 


STEMS  33 

strawberry  plant.     They  are  attached  to  the  old  plant  for 
but  one  season.     Runners  may  branch. 

6.  Lianas. — ^A  liana  is  a  climbing  stem,  gaining  mechanical 
support  only  from  another  plant.  Common  hanas  are  the 
grape,  Virginia  creeper,  hop,  Japan  ivy  {Psedra  tricuspidata) 
and  morning  glory.  The  stems  of  lianas  are  slender,  long, 
and  have  insufficient'  strengthening  tissue  to  hold  them 
perfectly  erect.  Hop  stems  always  wind  about  the  support 
clockwise  (Fig.  102).  Such  a  twiner  is  destrorse.  The  twin- 
ing stem  of  Virginia  creeper  bears  fleshy,  yellowish  air  roots 
which  may  aid  the  plant  in  adhering  to  its  support.  Of 
greater  value  to  the  Virginia  creeper  plant,  in  this  regard, 
however,  are  the  highly  specialized  branches — tendrils.  In 
this  case,  a  tendril  ends  in  a  knob  which  flattens  out,  when 
it  comes  into  contact  with  a  surface,  and  adheres  to  that 
surface  by  a  mucilaginous  disk-shaped  structure. 

7.  Spines.- — Some  spines  are  reduced  stem  structures,  as 
is  the  case  in  the  honey-locust,  hawthorn,  wild  crab,  etc. 
Many  small  spines,  such  as  are  found  in  gooseberries,  cacti, 
and  roses,  for  example,  are  outgrowths  of  the  stem.  It 
seems  that  spines  are  induced  by  an  excessive  loss  of  water 
from  the  plant,  and  a  low  absorption  rate,  such  as  occur 
under  desert  and  semi-desert  conditions. 

STRUCTURE  OF  STEMS 

The  Young  Dicot  Stem.— Let  us  cut  a  middle  lengthwise 
section  of  a  young  dicot  stem  (Fig.  15).  This  section  will 
cut  the  growing  point  (bud)  of  the  stem,  and  the  older  parts 
back  of  the  growing  point.  We  see  that  the  stem  becomes 
progressively  older  farther  and  farther  back  from  the  tip. 
The  cells  at  the  growing  point  make  up  a  tissue  known  as 
meristem  tissue  (undifferentiated  tissue)..  Although  they 
3 


34 


BOTANY   OF   CROP  PLANTS 


are  similar  in  appearance,  it  is  quite  evident  that  they  are 
capable  of  developing  into  different  tissues.     Just  back  of 


r  Xylemfroni   the   procamblun 

Cylem  from  the  procamblum  xvlem  f rom   the  cambium 

Xylem  from  the  cambium  .phloem  from  the  procamblum  and  cambium 

rhloem  from  the  procamblum  and  cambium  miuouiiium       <=  w 

Fig.  15. — Diagram  showing  the  evolution  of  tissues  from  the  primordial 
meristem  down  to  the  beginning  of  cambial  activity.     {After  Stevens.) 

the  growing  point,  we  note  that  the  cells  have  differentiated 
into  three  main  regions:  epidermis,  ground  meristem,  and 


STEMS 


35 


:::^^ 

OOOo 

IP 

%oc>o 

ooot^o 

-S=^^ 

OOooO 

==-__ 

ill 

^^ 

.=^ 

.S: 

er.^1!^ 

o°o?S 

^^ 

^^5=-- 

So^'^O 

OO  o° 

OOoO 

S 

,==» 

procambium  strands.  These  three  regions  are  best  shown 
in  a  cross-section  (Fig.  15).  In  a  little  older  portion 
of  the  stem,  such  as  shown  in  a  section  further  back 
(Fig.  15),  further  differentiation 
has  taken  place,  which  changes 
involve  the  ground  meristem  and 
the  procambium.  The  vascular 
bundle  is  composed  of  three  re- 
gions :  phloem,  cambium  and  xylem. 
The  center  of  the  stem  is  made  up 
of  large,  loosely  fitting  cells  which 
constitute  the  pith  or  medulla. 
Radiating  from  the  medulla  out 
between  the  vascular  bundles  are 
a  number  of  cells  which  make  up 
the  medullary  ray. 

Dicot  Vascular  Bundle. — De- 
tailed examination  of  a  dicot  vas- 
cular bundle  in  cross-  and  longitu- 
dinal sections  shows  each  of  its 
three  parts  to  be  made  up  of 
characteristic  structural  elements. 

Phloem. — In  the  phloem  are 
sieve  tubes,  companion  cells,  and 
phloem  parenchyma.  Each  sieve 
tube  is  a  single  cell,  much  elon- 
gated and  modified  for  conduc- 
tion. The  end  walls  of  sieve  tubes 
(Fig.  16)  are  thickened,  and  per- 
forated by  a  great  number  of  holes, 

and  thus  resemble  a  sieve.  Each  sieve  tube  is  adjoined  by 
a  single  row  of  small  cells,  the  companion  cells,  which  run 
parallel  to  it.     Phloem  parenchyma   cells    are    somewhat 


F  '  "^^ 

Fig.  16. — Vascular  elements. 
A,  annular  tracheal  tube;  B, 
spiral  tracheal  tube;  C,  reticu- 
lated tracheal  tube;  D,  pitted 
tracheal  tube;  E,  cross-section 
through  plate  of  sieve  tube, 
and  adjoining  companion  cell; 
F,  lengthwise  section  of  sieve 
tube;  G,  portions  of  two  com- 
panion cells.  (£,  F,  and  G 
after  Strashurger.) 


36  BOTANY  OF  CROP  PLANTS 

vertically  elongated,  but  they  do  not  reach  any  consider- 
able size. 

Functions  of  Phloem  Elements. — The  functions  of  these 
three  elements  of  the  phloem  are  as  follows : 

1.  Sieve  Tubes. — Conduction  of  soluble  carbohydrates, 
amido-acids  and  proteins. 

2.  Companion  Cells. — Although  sieve  tubes  lose  their 
nuclei  before  the  end  of  the  first  year,  they  do  not  die;  hence, 
it  is  thought  that  companion  cells  extend  their  influence  to 
the  sieve  tubes,  enabling  them  to  carry  on  the  Hfe  processes 
for  which  a  nucleus  seems  necessary. 

3.  Phloem  Parenchyma. — The  cells  of  this  region  store  food 
material  or  conduct  it  short  distances  in  the  stem. 

Cambium. — The  cambium  layer  is  composed  of  one  or 
more  rows  of  small  cells,  flattened  in  planes  that  run  at 
right  angles  to  a  radius  of  the  stem.  They  are  thin- walled 
cells,  rich  in  protoplasm,  and  capable  of  rapid  cell  division 
and  growth.  The  cambium  is  in  fact  the  growing  layer  of 
the  stem.  In  grafting,  one  stem,  the  scion,  is  inserted 
into  another  stem,  the  stock,  in  such  a  way  as  to  bring  the 
two  cambium  layers  together.  The  cells  of  these  layers 
possess  the  power  of  growth,  and  after  a  time  there  is  a 
union. 

Xylem  (Wood). — The  chief  structural  elements  of  the 
xylem  or  wood  portion  of  the  vascular  bundle  are:  tracheal 
tubes,  tracheids,  wood  fibers  and  wood  parenchyma.  The 
tracheal  or  water  tubes  are  long,  large,  tubes  with  thick 
walls.  They  have  been  formed  by  the  elongation  and  en- 
largement of  rows  of  cells,  the  common  end  walls  of  which 
have  totally  or  partially  dissolved,  leaving  a  duct  of  consider- 
able length.  The"  walls  of  the  tracheal  tubes  become  thick- 
ened, and  the  thickening  material  {lignin)  is  laid  down  on 
the  inside  of  the  walls  in  various  patterns. 


STEMS  37 

Kinds  of  Tracheal  Tubes  (Fig.  i6). — There  are  the  fol- 
lowing sorts  of  tracheal  tubes: 

1.  Annular  Tracheal  Tubes. — Here  and  there  in  the  tube 
are  thickened  rings  of  lignin,  which  have  the  appearance  of 
barrel  hoops. 

2.  Spiral  Tracheal  Tubes. — The  thickening  material  is  in 
the  form  of  a  loose  spiral. 

3.  Reticulated  Tracheal  Tubes. — In  these,  the 
strengthening  material  is  laid  down  in  such  a 
fashion  as  to  form  a  network  on  the  wall. 

4.  Dotted  or  Pitted  Tracheal  Tubes. — In  these, 
lignin  has  been  deposited  over  the  inner  wall  in 
such  a  manlier  as  to  leave  numerous  circular  thin 
places,  which  give  the  tube  a  dotted  or  pitted 
appearance. 

Tracheids  (Fig.  17)  are  single  cells,  elongated 
and  modified.  They  have  thick,  lignified  walls 
with  numerous  bordered  pits.  In  shape  tracheids 
are  like  a  spindle,  and  they  fit  closely  together 
making  up  a  strong  supporting  tissue.  Trache"d 

Wood  parenchyma  cells  are  usually  thin-walled  with  bor- 
and  with  unbordered  pits.  ^^^   ^^  ^' 

Wood  fibers  are  long,  taper-pointed  at  the  ends  and  thick- 
walled.     The  pits  are  unbordered. 

Functions  of  Wood  Elements. — The  functions  of  the  dif- 
ferent wood  (xylem)  elements  are  as  follows: 

1.  Tracheal  Tubes. — (a)  Carry  water  and  Solutes  from  the 
soil  to  and  throughout  the  leaves;  {b)  give  strength  to  the 
stem. 

2.  Tracheids. — (a)  Carry  water  and  solutes;  {b)  give 
strength  to  the  stem. 

3.  Wood  Parenchyma. — (a)  Store  water  and  foods;  {b}  and 
also  conduct  them  short  distances. 


^8  BOTANY   OF   CROP   PLANTS 

4.  Wood  Fibers.— Give  strength  to  the  stem. 

Growth  in  Thickness  of  Dicot  Stem. — Medullary  ray  cells 
give  rise  to  cambium  that  joins  with  the  cambium  in  the 
vascular  bundles.  Thus  there  is  formed  a  continuous  cam- 
bium ring  (Fig.  15).  At  the  end  of  the  first  year  of  growth 
or  the  beginning  of  the  second,  another  sort  of  cambium, 
called  cork  cambium,  is  differentiated  in  the  outer  cortex. 
Growth  in  thickness  of  the  stem  consists  then  in  the  produc- 
tion and  growth  of  new  cells  from:  (i)  cambium  of  vascular 
ring,  and  (2)  cork  cambium.  The  cambium  cells  of  the 
vascular  ring  may  differentiate  into  xylem,  or  phloem,  or 
remain  cambium.  Each  cambium  cell  divides  by  a  wall 
which  is  parallel  with  a  tangent  to  the  outside  of  the  stem. 
If  the  inner  cell  resulting  from  the  division  becomes  a  xylem 
element,  the  outer  usually  remains  cambium.  On  the  other 
hand,  if  the  outer  cell  resulting  from  the  division  becomes  a 
phloem  element,  the  inner  remains  cambium.  Hence,  by  a 
division  of  cambium  cells  of  the  vascular  ring,  new  xylem 
is  laid  down  on  the  outside  of  the  old  xylem,  and  new  phloem 
is  laid  down  on  the  inside  of  the  old  phloem.  Not  only 
do  the  vascular  bundles  grow  in  a  radial  direction,  but  also 
somewhat  laterally.  This  lateral  growth  of  existing  vascular 
bundles,  together  with  the  formation  of  new  ones  between 
the  old  ones,  brings  about  a  narrowing  of  the  medullary  rays, 
so  that  in  an  old  stem  they  appear  as  mere  lines  or  rays  radiat- 
ing from  the  pith  or  medulla.  And,  furthermore,  the  wood 
comes  to  form  quite  a  solid  ring,  as  does  also  the  phloem. 

In  addition  to  the  increase  in  stem  thickness  by  the  pro- 
duction of  more  xylem  and  phloem^  the  cork  cambium  cells 
aid  in  this  process.  Cork  cambium  cells  which  divide  by  a 
wall  that  is  parallel  to  a  tangent  of  the  stem,  give  rise  to 
cork  tissue,  and  to  secondary  cortex.  Hence,  each  year,  there 
are  produced  in  the  dicot  stem: 


STEMS 


39 


1.  Wood,  on  outside  of  old  wood. 

2.  Phloem,  on  inside  of  old  phloem. 

3.  Cork,  on  inside  of  old  cork. 

4.  Secondary  cortex,  on  outside  of  old  cortex. 

A  two-year  old  woody  dicot  stem  has  the  following  general 
structure : 

1.  Bark,  consisting  of  the  following  parts  in  order  from 
outside  to  inside:  Cork,  cork  cambium,  secondary  cortex, 
primary  cortex,  primary 
phloem,  secondary  phloem. 

2.  Cambium  of  vascular 
bundle. 

3.  Wood,  consisting  of 
two  layers,  the  youngest 
toward  the  outside. 

4.  FUh. 

5.  Medullary  rays,  each 
ray  of  several  rows  of 
thin-walled  cells  running 
from  the  medulla  to  the 
outer  edge  of  the  phloem. 

Monocot  Stems. — The 
corn  stalk  is  an  excellent 
type  of  a  monocot  stem. 
In  this,  as  shown  in  cross-section  of  the  stem  in  Fig.  18, 
the  vascular  bundles  (fibers)  are  scattered  throughout  the 
ground  tissue.  They  do  not  form  a  definite  "vascular  ring" 
as  in  dicot  stems.  Moreover,  the  vascular  bundles  of  most 
monocots  do  not  possess  cambium,  as  in  dicot  stems.  Hence, 
new  phloem  and  xylem  are  not  produced  each  season,  and 
consequently  there  are  no  annual  rings  formed.  Growth  of 
monocot  stems  results  from  (i)  simple  enlargement  of  cells 
derived  from  primary  meristem  tissue,  and  in  some  instances 


Fig.  18. — Cross-section  of  cornstalk 
stem;  a,  epidermis;  b,  cortex  and  peri- 
cycle;  c,  ground  tissue.     (After  Stevens.) 


40  BOTANY  OF  CROP  PLANTS 

from  (2)  the  formation  de  novo  of  vascular  bundles  from 
cells  that  have  retained  their  meristematic  power. 

Annual  Rings. — An  annual  ring,  as  generally  understood, 
is  one  year's  growth  of  wood  (xylem).  The  ring  varies  in 
width,  depending  upon  the  time  in  the  life  of  the  plant  it  was 
formed,  and  upon  seasonal  climatic  conditions.  Further- 
more, it  is  known  that  some  trees  grow  rapidly,  producing 
wide  annual  rings,  while  it  is  a  specific  character  of  others 
to  grow  slowly,  i.e.,  produce  narrow  annual  rings. 

There  is  usually  a  marked  difference  in  the  wood  formed  in 
the  spring  and  early  summer,  and  that  produced  in  late 
summer  and  fall.  In  early  or  so-called  "summer  wood," 
tracheal  tubes  are  large  and  quite  numerous;  in  late  or 
"autumn  wood,"  tracheal  tubes  are  smaller  and  fewer,  and 
tracheids  and  wood  fibers  are  relatively  more  abundant. 
Hence,  "autumn  wood"  has  more  strength  than  summer 
wood.  It  is  readily  seen  that  the  autumn  wood  of  one  year 
(say  1916)  is  adjacent  to  the  spring  wood  of  the  following 
year  (19 17).  "Soft  wood"  is  usually  one  which  grows 
rapidly,  and  is  difuse  porous,  that  is,  tracheal  tubes  are 
rather  small  and  uniform  in  size  and  evenly  distributed 
throughout  the  year's  growth.  "Hard  wood"  is  usually  a 
comparatively  slow-growing  wood,  and  is  ring  porous,  that 
is,  the  tracheal  tubes  of  the  spring  and  early  summer  are 
large  and  numerous,  while  the  autumn  wood  is  solid  as  a 
consequence  of  the  relatively  greater  abundance  of  tracheids 
and  wood  fibers. 

Bark. — The  term  "bark"  with  us  includes  all  that  portion 
of  the  stem  down  to  the  cambium  layer.  When  the  bark 
of  a  tree  is  peeled  off,  there  are  removed  the  following 
layers  in  order  from  outside  to  inside:  cork,  cork  cambium, 
cortex,  phloem,  and  portions  of  cambium.  The  cleavage  Hne 
is  the  cambium  zone. 


STEMS  41 

The  Work  of  Stems. — (i)  The  stems  of  trees,  shrubs  and 
common  herbs  are  mainly  concerned  in  the  conduction  of 
water  and  solutes  from  the  soil,  and  of  food  materials.  The 
need  for  a  conductive  system  first  arose  in  the  plant  kingdom 
when  the  food-making  organs  of  the  plant  became  elevated 
above  the  soil  or  water  surface.  (2)  The  stem  also  is  a 
support  to  the  other  organs  of  the  plant,  and  it  brings  into 
display  the  leaves,  and  flowers.  The  leaves  are  brought 
into  a  position  where  they  may  receive  the  light  to  advantage, 
and  flowers  are  placed  where  their  pollen  may  be  disseminated 
by  wind  or  bees,  and  seeds  may  be  more  easily  spread.  (3) 
In  addition  to  conduction  and  support,  stems  may  store 
food  material,  water  and  various  waste  products.  In  our 
woody  perennials,  such  as  the  apple  or  peach,  for  example, 
an  abundance  of  food  material  is  stored  during  the  winter 
in  the  medullary  ray  cells,  also,  in  wood  parenchyma,  and  in 
that  portion  of  the  pith  adjacent  to  wood,  and  sometimes 
in  all  of  the  pith  cells;  portions  of  the  phloem,  and  cortex 
may  also  store  food.  The  stems  of  such  plants  as  the  giant 
cactus,  and  other  cacti,  store  large  quantities  of  water. 
Some  stems,  such  as  the  potato  tuber,  bulb,  corm  and  root- 
stock,  are  heavily  loaded  with  stored  food  material.  (4) 
Young  stems  that  contain  chlorophyll  in  their  outer  layers 
possess  the  power  of  manufacturing  carbohydrates,  just  as 
do  green  leaves. 


CHAPTER  V 
LEAVES 

Development  of  Leaves.^ — ^Leaves  appear  at  the  growing 
point  of  a  stem,  as  lateral  protuberances  (Fig.  15)  consist- 
ing at  first  of  a  shapeless  mass  of  cells.  We  call  this  group  of 
cells  the  primordial  leaf.  By  further  cell  division  and  dif- 
ferentiation (becoming  different  from  each  other)  of  these 
few  cells  the  adult  leaf  arises.  In  the  embryos  of  seeds 
the  first  few  leaves  are  already  formed,  and  even  in  this 
early  stage  may  bear  some  resemblance  in  shape  to  the 
adult  leaves. 

Parts  of  Leaf. — Most  leaves  have  two  distinct  parts: 
hlade  and  petiole  (leaf  stalk).  Some  leaves,  as  those  of  peas 
and  beans,  have  two  small,  leaf-like  structures  at  the  base 
of  the  petiole.  These  are  stipules  (Fig.  19).  The  petiole  is 
sometimes  absent,  the  blade  being  mounted  directly  on  the 
stem.  Such  a  leaf  is  said  to  be  sessile.  Vascular  bundles  run 
from  the  stem  out  through  the  petiole  into  the  blade,  where 
they  branch  to  form  the  network  of  veins.  The  veins  not 
only  carry  water,  solutes  and  food  materials,  but  also  form 
a  framework  for  the  softer  tissue  of  the  leaf. 

Kinds  of  Leaves. — It  is  possible  to  classify  leaves  in  many 
different  ways.  Common  green  leaves  that  we  are  all 
familiar  with  are  usually  called  foliage  leaves.  They  are  the 
chief  food-making  organs  of  all  ordinary  plants.  However, 
there  are  many  leaves  that  do  not  possess  green  coloring 
matter  (chlorophyll)  and  hence,  have  no  food-making  power. 
42 


LEAVES 


43 


tendrils 


-jleajleh 


As  examples  of  the  latter,  may  be  mentioned  the  small 
scale  leaves  on  underground  stems,  the  scales  enwrapping 
the  growing  point  in  buds,  the  bracts  in  grass  inflorescences, 
and  the  petals,  stamens  and  car- 
pels of  flowers. 

We  look  upon  ordinary  foliage 
leaves  as  the  most  common,  and 
hence  "normal,"  sorts  of  leaves. 
We  would  regard  scale  leaves, 
bracts,  bud  scales,  and  flower 
parts  as  "modified"  leaves. 

Leaves  may  function  as  (i) 
food-making  organs  (foliage 
leaves),  (2)  protective  structures 
(scales),  (3)  reproductive  organs 
(floral  organs),  and  (4)  as  storage 
organs.  The  fleshy  leaves  that 
make  up  the  bulb  of  onion  are 
good  examples  of  leaves  used  for 
storage. 

Foliage  leaves  are  either  par- 
allel-veined or  netted-veined.  In 
leaves  with  parallel  venation,  there 
are  many  veins,  about,  equal  in 
size,  running  parallel,  and  joined 
by  inconspicuous  veinlets.  This 
type  of  venation  is  characteristic 
of  the  leaves  of. grasses,  sedges, 
rushes,  liHes  and  most  all  other 
monocotyledonous  plants.  In 
leaves  with  netted  venation,  which 
is  so  well  illustrated  in  leaves  of  apple,  oak,  maple,  potato, 
cabbage  and  other  dicotyledonous  plants,  there  are  a  few 


'^stipules 


Fig.  19. — A  single  compound 
leaf  of  sweet  pea. 


44  BOTANY  OF  CROP  PLANTS 

prominent  veins  from  which  arise  numerous  minor  veins, 
thus  forming  quite  a  conspicuous  network. 

Leaves  are  often  classed  as  simple  or  compound.  The  apple 
leaf  is  an  example  of  a  simple  leaf  (Fig.  1 59) .  In  this  there 
is  an  undivided  blade.  The  bean,  pea,  carrot  or  parsnip  leaf 
is  compound  (Fig.  19).  The  blade  is  divided  into  a  number 
of  segments,  or  leaflets. 

We  may  classify  leaves  as  to  their  arrangement  on  the 
stem.  Leaf  arrangement  is  the  same  as  bud  arrangement, 
for  ordinarily  a  bud  arises  in  the  axil  of  each  leaf.  They 
may  be  alternate,  opposite  or  whorled  (see  page  25). 

Leaves  vary  widely  in  size,  shape,  character  of  margin,  and 
base,  texture,  thickness,  nature  of  epidermal  coverings,  etc. 
Some  of  these  variations  will  be  mentioned  throughout  the 
pages  that  follow. 

Structure  of  Leaves. — The  structure  of  a  leaf  is  best  shown 
in  a  cross-section  ,(Fig.  20) .  The  upper  epidermis,  usually 
consists  of  a  single  row  of  cells.  Below  it,  is  the  palisade 
layer,  composed  of  one  or  more  rows  of  cells  the  long  axes 
of  which  are  perpendicular  to  the  leaf  surface.  Below  the 
paHsade  cells  is  the  spongy  parenchyma,  varying  in  thick- 
ness, and  composed  of  rather  irregularly  shaped  cells  that 
fit  together  loosely,  thus  leaving  intercellular  spaces  (air 
spaces) .  The  lower  epidermis  is  seldom  more  than  one  layer 
of  cells  thick.  Chloroplastids  are  abundant  in  palisade  and 
spongy  parenchyma  cells,  but  absent  from  all  epidermal  cells 
except  the  guard  cells  of  stomata. 

The  outer  wall  of  epidermal  cells  is  normally  thicker  than 
radial  or  inner  walls.  Cutin,  a  fatty  substance,  highly  im- 
pervious to  water,  is  deposited  on  the  outer  wall,  to  form  a 
layer  called  the  cuticle.  A  thick  cuticle  is  a  common  char- 
acteristic of  leaves  growing  in  arid  situations.  The  same 
variety  will  developa  thicker  cuticle  under  arid  conditions 


LEAVES 


45 
A  thick 


than  when  growing  where  there  is  ample  water, 
cuticle  is  a  good  drought-resistant  character. 

The  epidermal  cells  do  not  form  a  continuous  layer  over 
the  two  leaf  surfaces.  There  are  numerous  pores  or  open 
ings,  the  stomata  (singular  stoma,  a  mouth)  (Fig.  20).  Each 
stoma  is  bounded  by  two  modified  epidermal  cells,  differing 


Fig.  20. — Diagram  showing  the  structure  of  a  representative  leaf. 
{After  Stevens.) 

from  ordinary  epidermal  cells  in  form,  in  their  ability  to 
change  shape,  and  in  the  possession  of  chloroplastids.  These 
are  the  guard  cells. 

Leaves  possess  many  different  kinds  of  surface  peculiarities, 
such  as  hairs,  scales,  wax  and  resin  deposits.  These  are 
features  which  tend  to  retard  water  loss  from  the  leaf  surface. 

There  is  the  widest  variation  in  leaf  structure.    That 


46  BOTANY  OF  CROP  PLANTS 

described  above  is  typical  of  dicot  leaves  growing  in  situa- 
tions with  a  moderate  water  supply.  Water  leaves  are 
thin  and  have  no  palisade  tissue.  Palisade  tissue  is  also 
absent  in  the  leaves  of  grasses.  The  leaves  of  plants  grow- 
ing in  arid  situations  are  usually  thick.  The  increased 
thickness  is  commonly  due  to  an  increase  in  the  number  of 
rows  of  palisade  cells.  Palisade  may  develop  on  both  upper 
and  lower  surfaces.  Some  leaves  have  palisade  tissue  from 
epidermis  to  epidermis.  The  thickness  of  leaves  growing  in 
arid  conditions  may  also  be,  in  part,  the  result  of  the  de- 
velopment of  a  very  thick  cuticle. 

The  Work  of  Foliage  Leaves. — ^Leaves  are  very  important 
organs  of  the  plant.  We  are  all  familiar  with  the  injury  to 
a  plant  that  results  from  defoHation  through  any  cause,  or 
from  disease  of  leaves,  or  from  their  meager  development. 
We  have  learned  to  associate  an  abundance  of  bright  green 
leaves  with  plant  vigor,  just  as  we  associate  a  rosy  com- 
plexion with  health  in  people.  And,  with  but  few  excep- 
tions, we  may  judge  of  the  health  of  a  plant  by  its  leaf 
development  and  color. 

Carbohydrates  are  made  by  green  plants  only,  and  only 
by  those  cells  of  green  plants  that  possess  chlorophyll.  The 
cells  of  roots  and  other  underground  plant  parts,  and  all 
those  cells  of  the  plant  so  far  removed  from  the  surface  as  to 
be  beyond  the  influence  of  light,  do  not  have  chlorophyll, 
and  hence,  have  no  power  of  making  carbohydrates.  Other 
than  that  in  the  relatively  small  amount  of  green  tissue  in 
young  stems  and  in  the  sepals  of  flowers,  all  the  carbohydrate 
of  the  plant  is  made  in  the  chlorophyll-bearing  cells  of  leaves. 
The  manufacture  of  carbohydrate  by  green  tissue  is  called 
carbohydrate  synthesis  or  photosynthesis.  When  we  realize 
that  carbohydrates  form  the  basis  of  all  the  other  more  com- 
plex foods  of  the  plant  body,  such  as  fats,  amides  and 


LEAVES  47 

proteins,  we  see  the  great  importance  of  a  healthy  leaf 
development. 

In  addition  to  their  important  work  of  carbohydrate 
synthesis,  the  synthesis  of  the  fats,  amides  and  proteins  is 
carried  on  to  a  large  extent  in  leaf  cells.  We  may  truly  say, 
then,  that  leaves  are  the  food-making  organs  of  a  plant. 

Leaves  are  also  the  chief  transpiring  (water-losing)  organs 
of  the  plant.  Practically  all  of  the  water  that  escapes  from 
a  plant  passes  out  through  the  leaves,  chiefly  through  the 
stomata.  When  in  a  healthy  growing  condition,  there  is  a 
continuous  stream  (transpiration  stream)  of  water  from  the 
roots  to  the  leaves. 

The  leaves  of  many  succulent  plants,  such  as  Agave, 
Russian  thistle,  salt  wort,  stone  crop,  and  others  serve  as 
storage  places  for  water.  Agave  leaves  may  also  store 
food.  The  onion  bulb  is  made  up  of  a  very  short  stem  bear- 
ing numerous,  overlapping,  fleshy  leaves  in  which  consider- 
able quantities  of  food  are  stored. 

The  leaves  of  the  sundew  {Drosera),  and  pitcher  plants 
{Sarracenia  and  Nepenthes)  are  highly  modified  as  special 
organs  that  catch,  digest  and  absorb  insects. 


CHAPTER  VI 


FLOWERS 

Parts  of  Representative  Flower. — A  representative  flower 

such  as  shown  in  Fig.  21 
has  the  following  parts 
taken  in  order  from  the 
outside  to  the  inside: 

1.  Calyx,  made  up  of 
sepals,  which  are  green, 
and  enclose  the  other 
flower  parts  in  the  bud. 

2.  Corolla,  made  up  of 
petals,  which  are  usually 
the  colored  portions  of  the 
flower. 

3.  Stamens,  each  made 
up  of  a  stalk  or  filament 
at  the  tip  of  which  is 
the  anther,  bearing  pollen 

5"*^v^        V^^X^Q  ^   Pistil,   which   has   a 

,^  swollen  basal  portion,  (i) 

\^^y\j  If  .     the  omr'^,  (2)  a  style,  slen- 

^^^^^^"^^ (k  W  der  stalk  leading  from  the 

ovary,  and  terminating  in 
(3)  a  stigma,  which  is  re- 
ceptive to  pollen.  Within 
the  ovary  are  the  young 
ovules,  the  bodies  which  become  seeds. 
48 


Fig.  21. — Flax.     A,  floral  diagram — 
c,  calyx;  co,  corolla;  s,  stamens;  p,  pistil. 

B,  median  lengthwise  section  of  flower. 

C,  calyx  and  corolla  removed.     D,  fruit, 
external  view.     E,  cross-section  of  fruit. 


FLOWERS 


49 


All  the  flower  parts  mentioned  above,  in  the  representative 
flower,  are  attached  to  the  end  of  the  flower  stalk,  the 
receptacle  or  torus.  The  calyx  and  corolla  taken  together 
constitute  the  perianth. 

We  shall  see  that  there  are  many  different  sorts  of  flowers 
in  the  families  of  seed  plants.  They  differ  widely  in  size, 
form,  color,  and  in  the  shapes  of  the  various  parts. 

Development  of  the  Flower. — The  primordia  of  flower 
parts  arise  as  protuberances  from  the  young  receptacle  (Fig. 
15).     As   a   rule,  the   sepals,  petals,  stamens  and  carpels 


Fig.  22. — Cross-section  of  a  mature  lily  anther.  The  pairs  of  pollen  cham- 
bers unite  to  form  two  pollen  sacs,  filled  with  pollen  grains;  s,  modified  epi- 
dermal cells  at  line  of  splitting.  (From  a  Text-book  of  Botany  by  Coulter, 
Barnes,  and  Cowles.  Copyright  by  the  American  Book  Company,  Publishers.) 


appear  in  the  order  named,  as  described  in  the  case  of  the 
apple  flower  on  page  366.  This  order  of  floral  succession  is 
said  to  be  acropetal.  Although  this  is  the  prevaiHng  order, 
there  are  different  types.  For  example,  in  some  mustards 
the  petals  are  the  last  to  appear,  and  in  some  roses  the  carpel 
primordia  appear  before  the  stamens. 
Stamens. — Ordinarily,  the  anther  is  held  upon  a  filament 


50  BOTANY  OF  CROP  PLANTS 

or  stalk.  When  the  filament  is  absent,  the  anther  is  said 
to  be  sessile.  A  cross-section  of  an  immature  anther  is 
seen  to  have  four  chambers  or  locules,  each  with  a  number 
of  pollen  mother  cells;  each  pollen  mother  cell  normally 
divides  to  form  four  pollen  grains.  As  the  anther  matures 
the  pairs  of  locules  unite,  thus  forming  two  pollen  sacs  in 
each  anther.  Finally,  each  sac  splits  open  (dehisces)  allow- 
ing the  pollen  to  escape  (Fig.  22). 

Matiire  Pollen  Grain. — When  the  pollen  grain  is  mature, 
it  consists  of  a  wall  surrounding  a  protoplasmic  mass,  the 
essential  parts  of  which  are  a  tube  nucleus  and  a  generative 
nucleus.  At  the  time  of  pollen  germination  the  latter  di- 
vides into  two  sperm  or  male  nuclei. 

Pistil. — The  pistil  usually  consists  of  an  ovary,  style  and 
stigma.  The  seeds  are  borne  in  the  ovary.  A  cross-section 
of  a  simple  ovary  shows  it  to  have  one  locule  or  chamber 
with  one  or  more  ovules  attached  to  the  wall.  The  tissue  to 
which  the  ovule  or  ovules  are  attached  is  the  placenta. 
A  compound  ovary  (Figs.  21  and  131)  usually  has  two  or 
more  compartments,  with  an  ovule-bearing  tissue  (placenta) 
in  each.  We  may  also  speak  of  the  pistil  as  simple  or  com- 
pound. A  simple  pistil  has  one  carpel,  which  is  in  reality  a 
modified  leaf  bearing  one  or  more  seeds.  A  compound  pistil 
has  two  or  more  carpels.  When  the  carpels  are  separate, 
as  in  the  strawberry  (Fig.  151)  the  flower  is  said  to  be 
apocarpous;  when  united,  as  in  asparagus  (Fig.  99), 
syncarpous. 

Ovule. — Fig.  23  shows  an  ovule  just  before  fertilization. 
A  central  mass  of  tissue,  the  nucellus,  is  surrounded  by  an 
inner  and  an  outer  integument,  except  for  a  small  opening, 
the  micropyle.  Within  the  nucellus  is  the  embryo  sac,  at 
this  stage  consisting  of  eight  nuclei:  two  synergids,  one  egg 
nucleus,  three  antipodals,  and  two  polar  nuclei.     They  occupy 


FLOWERS 


51 


about  the  relative  positions  in  the  embryo  sac  as  shown  in 
Fig.  23. 

Pollination. — This  is  a  mechanical  process  in  which  pollen 
is  transferred  from  an  anther  to  a  stigma.  Pollen  may  be 
transferred  from  an  anther  to  the  stigma  in  the  same  flower. 


pollen  iube 


eqg  nucleus 


pericarp 
ouier  /niefi/item 
innerhhijvtneni 

nucellvi-' 
embrno  sac  -' 

polarnuc/ei 
aniipodals 


Fig.  23. — Diagram  of  a  simple  pistil  as  seen  in  lengthwise  section  showing  a 
single  ovule  just  prior  to  fertilization. 


This  is  termed  autogamy  or  close  pollination.  Or,  pollen 
may  be  carried  from  an  anther  to  a  stigma  of  another  flower 
on  the  same  individual  plant.  This  is  called  geitonogamy. 
Again,  pollen  may  be  transferred  from  an  anther  to  a  stigma 
of  a  flower  on  another  individual  plant.     This  is  termed 


52 


BOTANY   OP   CROP   PLANTS 


xenogamy,  or  cross-pollination.     Insects,  wind  and  water  are 
the  chief  agents  in  the  spread  of  pollen. 

Fertilization. — Fig.  23  is  a  diagram  of  an  ovary  with  a 
single  ovule  cut  lengthwise.  It  shows  a  stage  of  develop- 
ment of  the  ovule  about  at  the  time  when  the  pollen  grain 
has  reached  the  stigma.  As  has  been  said,  the  mature  pollen 
grain  consists  of  a  protoplasmic  mass  surrounded  by  a  rather 
thick  wall.  Three  nuclei  (Fig.  24)  constitute 
the  important  structures  in  the  pollen  grain. 
It  absorbs  water  and  nutrient  materials  from 
the  stigmatic  surface,  and  grows  by  sending 
out  a  tube,  known  as  the  pollen  tube.  The 
tube  grows  downward  through  the  stigma, 
sometimes  in  a  tubular  passage,  or  when 
necessary,  secreting  enzymes  which  digest 
(render  soluble)  the  walls  of  cells  that  are  in 
its  path,  at  the  same  time  deriving  nourish- 
ment from  this  digested  material.  As  the 
tube  grows,  the  three  nuclei  keep  pretty  close 
to  the  tip,  the  tube  nucleus  in  the  lead,  with 
the  two  sperm  nuclei  (male  gametes)  follow- 
ing. The  tube  finally  reaches  the  ovule, 
takes  a  course  through  the  micropyle  and  comes  into  con- 
tact with  the  nucellus.  This  nucellar  tissue  is  penetrated, 
and  after  dissolution  of  the  wall  at  the  tip  of  the  pollen  tube, 
the  three  nuclei  are  discharged  into  the  embryo  sac.  The 
tube  nucleus  is  reabsorbed.  One  sperm  nucleus  unites  with 
the  egg  nucleus  (female  gamete)  to  form  the  zygote,  a  nuclear 
mass  which  contains  both  the  characters  of  the  plarit  fur- 
nishing the  pollen  -  (paternal  characters)  and  those  of  the 
plant  fertilized  (maternal  characters).  The  union  of  the 
male  gamete  (sperm  nucleus  of  pollen  tube)  with  female 
gamete  (egg  nucleus  of  embryo  sac)  is  fertilization.     It  is  a 


■tube  nucleus 

Fig.  24. — Ger- 
minating pollen 
grain.  {After 
Bergen  and  Cald- 
well.) 


FLOWERS  53 

sexual  process.  It  is  seen  to  differ  fundamentally  from 
pollination  which  is  simply  a  mechanical  -process.  The 
fertilized  embryo  nucleus  now  develops  into  a  young  plant 
(embryo).  The  synergids  and  antipodals  are  usually  dis- 
organized. In  grasses  and  lilies  and  some  other  plants,  so- 
called  double  fertilization  has  been  observed.  One  sperm 
nucleus  has  been  accounted  for,  as  uniting  with  the  embryo 
nucleus.  The  other  unites  with  the  two  polar  nuclei  of  the 
embryo  sac.  The  body  resulting  from  this  triple  fusion  also 
carries  both  maternal  and  paternal  characters.  It  grows 
and  develops  into  the  endosperm  of  the  seed.  Immediately 
following  fertilization,  there  is  a  series  of  changes  not  only 
in  the  ovule  which  results  in  a  seed,  but  in  the  ovary  wall  as 
well. 

Just  one  pollen  tube  penetrates  the  embryo  sac  to  bring 
about  fertilization.  Many  pollen  tubes,  even  hundreds, 
may  penetrate  the  style,  although  comparatively  few  may 
function  normally.  Those  which  do  not,  wither  and  die. 
We  may  be  sure  that  every  ovule  that  develops  into  a  seed 
has  been  visited  by  one,  and  only  one,  pollen  tube. 

Placentation. — We  said  that  the  placenta  is  the  tissue  in 
the  ovary  to  which  the  one  or  more  ovules  are  attached.  It 
is  traversed  by  vascular  bundles  from  which  branches  are 
given  off  to  the  ovules.  In  currants  and  gooseberries  (Fig. 
129)  the  placentae  are  on  the  ovary  wall.  Such  placentation 
is  said  to  be  parietal.  In  lilies  (Fig.  31^),  the  placentation 
is  axial,  or  central,  that  is,  the  placentae  are  on  the  ovary 
axis.  A  third  kind  of  placentation  is  the  free  central,  in 
which^the  ovules  are  attached  to  an  up-growth  of  the  floral 
axis  in  the  center  of  the  ovary,  which  is  not  connected  to 
the  ovary  wall  by  radial  partitions. 

Symmetry  of  Flower. — A  flower  such  as  the  apple,  cherry 
or  asparagus  can  be  divided  into  two  approximately  sym- 


54 


BOTANY   OF   CROP   PLANTS 


metrical  halves  by  any  diameter  (Figs.  156  and  162).  Such  a 
flower  is  said  to  be  radially  symmetrical,  or  acfinomorphic, 
or  regular.  Contrast  this  symmetry  with  that  in  such  flowers 
as  the  pea  or  bean  (Fig.  1 72^),  in  which  there  is  but  one  plane 
through  which  the  flower  can  be  divided  to  separate  it  into 
two  symmetrical  halves.  Such  a  flower  is  said  to  be  bi- 
laterally symmetrical,  or  zygomorphic,  or  irregular. 

Relative  Positions  of  Flower  Parts. — In  the  gooseberry  or 
currant  flower  (Fig.  129),  for  example,  the  ovary  is  below 
the  stamens,  corolla,  and  calyx,  and  is  said  to  be  inferior. .  A 
flower  with  an  inferior  ovary  is  said  to  be  epigynous  (above  the 
gynoecium  or  carpels) .  When  the  calyx,  corolla,  and  stamens 
are  inserted  on  the  receptacle  below  the  ovary,  the  ovary  is 
superior,  and  the  flower  hypogynous  (below  the  gyncecium). 
The  flowers  of  mustards  are  hypogynous.  There  is  a  third 
intermediate  type  of  flower,  well  illustrated  by  the  cherry 
(Figs.  157  and  163),  apple  (Fig.  157),  etc.,  in  which  the 
petals  and  stamens  are  inserted  on  a  calyx  rim  and  arise  at 
about  the  level  of  the  ovary.  In  such  a  case  the  ovary  is 
half-inferior  or  half -superior ,  and  the  flower  perigynous 
(around  the  gynoecium). 

Union  of  Flower  Parts.- — In  the  primitive  flower  type,  such 
as  the  buttercup,  the  sepals,  petals,  stamens  and  carpels  are 
all  separate  and  distinct.  A  more  or  less  complete  union  of 
the  parts  of  each  set  of  floral  leaves  may  take  place.  For 
example,  in  gooseberries  and  currants,  the  sepals  are  united 
to  form  a  calyx  tube,  in  the  potato  flower  the  petals  are  united 
to  form  a  corolla  tube,  in  the  cotton  flower  the  stamen  fila- 
ments are  joined,  and  in  many  instances — onion,  apple, 
orange,  and  others — the  carpels  are  united.  The  adjectives 
to  describe  these  various  cases  are  as  follows: 


FLOWERS  55 

Separate  United 

Sepals aposepalous  synsepalous 

Petals apopetalous  sympetalous 

o^                                         ,   J  1  ,  f  diadelphous  (2  groups) 

Stamens polydelphous  {            J 1  1.         /              \ 

^    -^      ^  [  monodelphous  (i  group) 

Carpels apocarpous  syncarpous 


Incomplete  Flowers. — The  representative  flower  described 
in  a  preceding  paragraph  had  all  four  floral  sets  of  organs 
present.  However,  one  or  more  of  these  sets  may  be  absent, 
and  in  this  case,  the  flower  is  incomplete.  Flowers  lacking 
petals  are  called  apetalous  (buckwheat).  When  both  sepals 
and  petals  are  absent,  the  flower  is  naked  (willows  and  cotton- 
woods)  .  In  the  majority  of  flowers,  both  stamens  and  pistils, 
the  essential  organs  of  a  flower,  are  present.  Such  a  flower 
is  said  to  be  perfect  or  hermaphrodite.  Some  flowers  have  but 
one  set  of  essential  organs,  either  stamens,  or  a  pistil.  A 
flower  with  stamens  only,  and  no  pistil,  or  a  flower  cluster 
(inflorescence)  composed  of  such  flowers,  is  said  to  be 
staminate.  On  the  other  hand,  a  flower  with  a  pistil  but  no 
stamens,  or  an  inflorescence,  composed  of  such  flowers,  is 
said  to  be  pistillate.  If  staminate  and  pistillate  inflores- 
cences are  on  different  plants,  the  species  is  said  to  be  "f/fce- 
cious."  In  some  dioecious  species  (hops),  the  staminate 
and  pistillate  inflorescences  are  very  unlike  in  appearance, 
while  in  other  dioecious  species  (salt-grass,  Distichlis),  the 
two  unisexual  inflorescences  are  very  similar.  If  staminate 
and  pistillate  inflorescences  are  on  the  same  individual  plant, 
it  is  said  to  be  "monoecious."  This  is  the  case  in  corn,  in 
which  the  "tassel"  (staminate  inflorescence)  and  the  "ear" 
(pistillate  inflorescence)  are  very  dissimilar  in  appearance. 

Inflorescence.— An  inflorescence  is  a  flower  cluster.  Its 
shape  and  the  arrangement  of  the  flowers  in  it  differ  with  the 
kind  of  plant.     There  are  three  general  classes  of  inflores- 


56  BOTANY  OF  CROP  PLANTS 

cences:  (i)  simple,  (2)  indeterminate  or  racemose,  and  (3) 
determinate  or  cymose. 

The  simple  type  is  well  represented  by  the  calla  Hly  or 
tulip,  in  which  one  flower  terminates  the  stalk.  Mustards 
and  currants  have  a  typical  indeterminate  or  racemose  in- 
florescence. In  this,  the  older  flowers  are  at  the  base  or 
outside  of  the  flower  group  and  the  younger  appear  in  order 
above  them.  Moreover,  the  growth  of  the  inflorescence 
may  continue  at  the  apex.  For  example,  in  a  cabbage  or 
radish  inflorescence,  flowers  may  be  opening  at  the  tip,  while 
at  the  base  pods  are  partially  mature.  Racemose  types  of 
inflorescences  are  the  true  raceme,  panicle,  corymb,  umbel, 
spike,  and  head.  These  will  be  described  when  they  are 
met  with  in  the  family  descriptions  that  follow.  The  cymose 
flower  cluster  is  one  in  which  the  older  flowers  are  on  the  in- 
side, and  the  younger  appear  in  order  toward  the  outside.  The 
length  of  a  flower  shoot  is  determined  by  the  terminal  flower. 
The  inflorescence  of  chickweeds  is  a  cyme. 


CHAPTER  VII 
FRUITS,  SEED,  AND  SEEDLINGS 

Development  of  the  Seed. — We  have  seen  how  a  male 
nucleus  of  the  pollen  tube  unites  with  the  egg  or  embryo 
(female)  nucleus  of  the  embryo  sac.  The  fertilized  egg 
then  starts  upon  a  series  of  'divisions,  and  by  growth  and 
development,  the  young  plant  or  embryo  is  formed.  It 
may  be  partially  or  totally  imbedded  in  the  endosperm. 
In  some  seeds  (bean),  the  endosperm  is  lacking,  and  the 
embryo  occupies  the  entire  space  within  the  seed  coats.  The 
cells  of  the  nucellus  are  in  part  absorbed  by  the  developing 
embryo,  and  at  most  the  nucellus  is  represented  by  a  very 
thin  and  compressed  layer  just  within  the  inner  integument. 
The  integuments  of  the  ovule  become  harder,  less  permeable, 
and  form  the  seed  coats.  The  micro pyle  is  still  evident  in  the 
mature  seed  as  a  small  opening. 

The  embryo  or  young  plant  has  three  main  parts:  (i) 
one  or  two  cotyledons;  (2)  the  hypocotyl,  which  includes  all 
of  the  embryo  below  the  cotyledons  and  terminates  in  the 
first  root  or  radicle;  and  (3)  the  growing  point  of  the  shoot, 
upon  which  are  a  few  leaves,  making  up  a  bud. 

The  parts  of  a  representative  mature  seed  may  be 
summarized  as  follows: 


Seed 


1.  Seed  coats. 

2.  Nucellus. 

3.  Endosperm. 

(Growing  point  of  shoot,  with  leaves  (bud) . 
Cotyledon  or  cotyledons. 
Hypocotyl,  terminating  in  the  young  root  or  radicle. 
57 


58  BOTANY  OF  CROP  PLANTS 

Development  of  the  Fruit. — The  stimulus  of  fertilization, 
which  is  not  well  understood,  extends  its  influence  not  only 
to  the  ovule,  but  to  the  ovary  as  well.  Coincident  with  the 
changes  resulting  in  the  mature  seed,  the  ovary  enlarges,  and 
its  walls  become  changed  both  physically  and  chemically. 
The  ovary  wall  (pericarp)  has  three  distinct  layers.  Named 
in  order  from  the  outside  to  the  inside,  these  are  the  exocarp, 
mesocarp  and  endocarp.  As  the  fruit  develops  the  changes 
that  occur  in  these  layers  may  differ.  For  example,  in  the 
cherry  or  plum,  the  exocarp  becomes  the  skin  of  the  fruit, 
the  mesocarp  becomes  thick  and  juicy  to  form  the  fleshy 
portion  of  the  fruit,  while  the  endocarp  takes  on  a  stony 
character. 

Fruit  and  Seed  Distinguished. — A  fruit,  botanically,  is 
the  matured  ovary,  with  its  seeds,  and  any  parts  of  the  flower 
which  may  be  closely  associated  with  it.  The  fruit  contains 
the  seed  or  seeds.  For  example,  the  entire  bean  pod  is  a 
fruit;  the  "beans"  within  are  the  seeds.  It  is  in  the  case  of 
dry,  one-seeded  fruits,  particularly,  that  distinction  needs  to 
be  made  between  fruit  and  seed.  For  example,  the  buck- 
wheat fruit  (achene)  or  grass  fruit  (grain)  is  commonly  called 
a  "seed."  But,  if  development  of  these  is  traced  and  their 
structure  carefully  examined,  they  are  seen  to  be  true  fruits, 
with  a  very  thin  pericarp  (ovary  wall)  enclosing  one  seed 
(Figs.  35  and  115). 

Kinds  of  Fruits. — No  attempt  will  be  made  at  this  place 
to  give  a  complete  classification  of  fruits.  We  will  describe 
the  different  kinds  as  we  meet  with  them  in  the  discussions 
of  crop  plants.  Fruits  with  a  dry  pericarp,  such  as  the  grain, 
achene,  capsule  and  pod,  are  designated  dry  fruits.  De- 
hiscent dry  fruits  (capsule,  pod,  foUicle)  split  open  at  maturity 
in  a  definite  way  permitting  the  seeds  to  escape.  Inde- 
hiscent  dry  fruits  (achene,  grain)  do  not  split  open  at  maturity 


TRUITS,   SEED,   AND   SEEDLINGS  59 

in  any  definite  way.  Fruits  with  a  fleshy  pericarp,  such  as 
the  berry,  are  called  fleshy  fruits. 

Germination  of  Seed. — The  seed  must  have  an  adequate 
supply  of  water,  oxygen  and  a  suitable  temperature  in  order 
to  germinate.  The  initiatory  stages  in  germination  are  the 
absorption  of  water  and  the  secretion  of  enzymes  in  the  seed, 
which  render  soluble  the  stored  food  material  necessary  to 
nourish  the  growing  embryo.  This  food  may  be  stored  in  the 
endosperm,  as  in  all  grains,  or  in  the  cotyledons,  as  in  beans 
and  peas.  The  embryo  is  dependent  upon  stored  food  for 
its  initial  growth.  The  swelling  of  the  seed,  due  to  water 
absorption  and  growth  of  the  embryo,  ruptures  the  seed  coats, 
and  the  young  shoot  and  primary  root  make  their  appearance. 
The  cotyledons  are  brought  above  ground  in  some  plants 
(beans,  squashes,  etc.)  and  constitute  the  temporary  or  seed- 
leaves.  They  may  develop  chlorophyll  and  make  food  for 
a  while.  The  true  foliage  leaves  develop,  partly  at  the  ex- 
pense of  the  food  stored  in  the  cotyledons,  which  gradually 
dwindle  away.  In  many  plants,  e.g.,  all  grasses,  the  coty- 
ledon remains  in  the  soil.  In  these  the  first  leaves  are  true 
foHage  leaves. 

As  soon  as  the  first  roots  are  established,  making  it  possible 
for  the  plant  to  absorb  water  and  mineral  nutrients  from  the 
soil,  and  a  few  leaves  are  formed,  the  young  plant  is  capable 
of  making  its  own  food  and  living  an  independent  Ufe.  It 
has  been  tided  through  its  early  stages  of  development  by 
food  stored  in  the  seed.  Generally  speaking,  large  seeds  of 
any  given  species  produce  more  vigorous  seedlings  than 
small  ones,  and  this  is  probably  correlated  with  a  greater 
abundance  of  stored  food  in  the  former. 


CHAPTER  VIII 
THE  CLASSIFICATION  AND  NAMING  OF  PLANTS 

That  subject  which  deals  with  the  arrangement  of  plants 
into  groups,  based  upon  their  structure  and  form,  is  desig- 
nated Systematic  Botany.  From  the  earliest  times,  man  has 
attempted  to  classify  the  large  and  varied  assemblage  of 
plants  which  he  has  found  on  the  earth.  There  have  been 
many  systems  of  classification,  some  "artificial,"  some 
"natural."  An  artificial  system  of  grouping  plants  may 
use  purely  arbitrary  bases;  it  may  be  convenient,  but  fail 
to  express  the  natural  affinities  of  plants.  For  example,  in 
an  artificial  system,  we  might  choose  to  put  all  those  plants 
with  red  flowers  into  one  group,  and  those  with  blue  flowers 
into  another  class,  and  so  on,  thus  basing  our  classification 
on  flower  color.  Or,  we  might  put  trees  into  one  group, 
shrubs  into  another,  and  herbs  into  still  another,  thus  basing 
the  grouping  on  size  and  growth  habit.  Obviously,  we 
would  throw  together  plants  which  have  no  natural  relation- 
ships, and  in  some  cases,  separate  those  which  are  naturally 
allied.  An  artificial  system  would  not  take  into  account  the 
evolutionary  tendencies  in  the  plant  world.  It  is  agreed 
that  one  system  of  classification  is  better  than  another  if  it 
more  accurately  expresses  the  natural  affinities  and  the 
evolutionary  tendencies  of  the  organisms  dealt  with. 

In  the  early  history  of  systematic  botany,  the  systems  of 

classification  were  largely  artificial.     As  the  knowledge  of 

plants  increased,  one  system  supplanted  another,  and  in 

most  cases  was  an  improvement  over  the  old  one.     One  of 

60 


THE   CLASSIFICATION   AND    NAMING   OF   PLANTS  6 1 

the  first  natural  systems  of  classifying  plants  (and  animals) 
was  that  of  Linnaeus.  The  first  edition  of  his  notable  work, 
Systema  Naturae,  was  published  in  1735.  There  follow 
the  systems  of  De  Jussieu  (1789),  De  Candolle  (1819), 
Eichler  (1883),  Bentham  and  Hooker  (1826-1883),  and  Eng- 
ler  and  Prantl  (1890-1896).  Two  recent  systems  are  those 
of  Bessey  (1907),  and  of  Schaffner  (1911). 

Reproductive  versus  Vegetative  Organs  in  Classification. 
— In  all  higher  plants,  reproductive  and  vegetative  organs 
differ  markedly  from  each  other.  Reproductive  tissues  are 
less  influenced  by  environmental  conditions  than  are  vege- 
tative tissues.  There  may  be  little  resemblance  between 
the  vegetative  portions  of  two  species,  although  their  repro- 
ductive structures  may  be  very  similar.  For  example,  the 
strawberry  and  raspberry  have  quite  different  growth  form, 
and  their  vegetative  organs  are  quite  dissimilar,  yet  the 
flowers  of  the  two  are  constructed  on  the  same  general  plan. 
On  the  other  hand,  two  plants  with  very  dissimilar  reproduc- 
tive structures,  i.e.,  having  little  natural  relationship,  may 
resemble  each  other  very  closely  in  their  general  vegetative 
appearance.  These  conditions  show  that,  although  vege- 
tative structures  may  be  modified  to  a  great  degree  under 
diverse  environmental  influences,  these  same  influences  do 
not  modify,  to  an  equal  extent,  the  reproductive  organs. 
Hence,  on  account  of  this  greater  stability  of  the  reproduc- 
tive structures  of  a  plant,  these  are  of  relatively  great  value 
in  showing  actual  relationships,  and  are  of  prime  importance 
in  classification. 

GROUPS  OF  PLANTS 

A  survey  of  the  plant  kingdom  shows  it  to  be  composed  of 
a  great  variety  of  plants,  differing  in  size,  in  structure,  in 
habitat,  and  in  method  of  living. 


62  BOTANY  OF  CROP  PLANTS 

The  "thallus  plants"  (Thallophytes)  include  the  simplest 
organisms.  This  group  is  divided  into  two  large  subdivi- 
sions, the  AlgcB  and  Fungi.  The  Algae  include  the  green 
scums  so  frequently  observed  upon  the  surface  of  pools, 
stagnant  ponds,  reservoirs,  ditches  and  streams.  They  are 
also  commonly  found  in  tanks  and  water  troughs,  and,  in 
such  places  may  render  the  water  objectionable  to  stock, 
especially  when  decay  sets  in.  The  brown  and  red  "sea 
weeds"  are  also  Algae.  The  Fungi  are  a  large  group  of 
plants,  probably  the  best  known  being  the  bacteria,  the 
molds  of  bread,  fruit,  and  cheese,  the  rusts  and  smuts  of  the 
cereals,  the  toadstools  and  mushrooms,  the  mildews,  and  the 
fungi  causing  such  well-known  diseases  as  blight  of  potato, 
alfalfa  leaf  spot,  apple  scab,  wilt  of  cucurbit,  etc. 

The  "moss  plants"  (Bryophytes)  include  the  liverworts, 
peat  mosses,  black  mosses,  and  common  mosses.  They  are 
a  group  of  comparatively  slight  economic  importance. 

The  "fern  plants"  (Pkridophytes)  are  represented  by  the 
true  ferns,  and  closely  allied  plants  such  as  the  horsetails  or 
scouring  rushes,  and  club  mosses.  Like  the  preceding 
groups,  fern  plants  do  not  produce  seed  but  reproduce  in  a 
much  simpler  fashion,  by  spores. 

The  highest  and  most  complex  group  is  the  "seed  plants" 
(Spermatophytes).  It  includes  the  Gymnospermce  (pines, 
spruces,  firs,  hemlocks,  cedars,  junipers  and  other  cone-bear- 
ing plants)  and  the  AngiospermcR  (higher  seed  plants  or 
flowering  plants).  All  the  common  crop  plants,  of  field, 
orchard,  and  garden  belong  to  the  Angiospermae.  In  the 
Gymnospermae  the  seeds  are  exposed,  while  in  Angio- 
spermae they  are  enclosed  in  a  case,  the  ovary  wall.  Angio- 
spermous  plants  fall  into  two  groups  (subclasses):  (i) 
Monocotyledpnes,  in  which  the  seeds  have  one  cotyledon',  the 
flower  parts  are  in  threes,  the  leaves  are  parallel-veined,  and 


THE  CLASStPlCATlON  AND   NAMING   OF  PLANTS  6;^ 

the  vascular  bundles  are  scattered  throughout  the  pith 
(examples:  cereals,  onions,  asparagus,  lilies);  (2)  Dicotyle- 
dones,  in  which  the  seeds  have  two  cotyledons,  the  flower 
parts  are  in  fours  or  fives,  the  leaves  are  netted-veined,  and 
the  vascular  bundles  are  in  the  form  of  a  cylinder  about  the 
pith  (examples:  buckwheat,  beet,  apple,  cherry,  mustard, 
cotton,  melon,  potato). 

Each  of  these  subclasses  is  further  subdivided.     A  com- 
plete classification  of  some  plant,  e.g.,  common  alfalfa,  will 
give  the  principal  subdivisions: 
Spermatophyta, 
Angiospermse, 
Dicotyledones, 
Order  Rosales, 

Family  Leguminosae, 
Genus  Medicago, 
Species  Medicago  sativa. 
The  order  ending  is  usually  "ales.''     Orders  are  subdivided 
into  families.      The  family  ending  is  commonly  "acecs"  or 
"cB."     Families  are  spHt  up  into  genera,  and  genera  into 
species.     The  number  of  families,  genera,  and  species  may 
be  large  or  small. 

THE  PLANT  KINGDOM 

Thallophytes— "Thallus  plants." 

Myxomycetes — slime  molds  or  slime  fungi. 
Schizophytes — "splitting  plants. " 

Cyanophyceae — blue-green  algae. 

Schizomycetes — bacteria. 
Algae — ^pond  scums,  sea  weeds,  etc. 

Chlorophyceae — green  algae. 

Phaeophyceae — brown  algae. 

Rhodophyceae — red  algae. 


64  BOTANY  OF  CROP  PLANTS 

Fungi — molds,  yeast,  mildews,  rusts,  smuts,  toadstools, 
lichens,  etc. 

Phycomycetes — algal-like  fungi. 

Ascomycetes — sac  fungi. 

Basidiomycetes— basidium  fungi. 
Bryophytes — "moss  plants." 
Hepaticag — liverworts. 
Musci — mosses. 
Pteridophytes — "fern  plants." 

Lycopodiales — club  mosses,  lycopods,  quillworts. 

Psilotales — two  small  living  genera. 

Sphenophyllales—a  single  Carboniferous  genus. 

Equisetales — horsetails. 

Ophioglossales — adder's  tongue,  moonwort. 

Filicales — true  ferns  and  water  ferns. 
Spermatophytes — "seed  plants." 

Gymnospermae— lower  seed  plants:  cycads,  ginkgo,  coni- 
fers, joint-firs,  etc. 
Angiospermae — higher  seed  plants. 

Monocotyledones. 

Dicotyledones. 

PLANT  NOMENCLATURE 

Scientific  Name.^ — The  system  of  nomenclature  in  use  by 
all  biologists  today  is  the  so-called  binomial  system.  The 
scientific  name  of  each  plant  (and  animal)  is  composed  of 
two  words.  For  example,  the  scientific  name  of  the  common 
garden  bean  is  Phaseolus  vulgaris  L.  The  first  word,  Phase- 
olus,  is  the  name  of  the  genus  (pi.  genera),  or  generic  name; 
the  second,  vulgaris,  is  the  name  of  the  species  (pi.  species)  or 
specific  name.  The  letter  "L"  following  the  scientific  name 
of  the  common  garden  bean  is  the  abbreviation  for  Linnaeus. 
Placed  in  this  position  after  the  name  of  the  plant,  it  signifies 


THE   CLASSIFICATION  AND   NAMING   OF'  PLANTS  6$ 

that  this  species  was  first  named  and  described  by  Linnaeus. 
This  description  may  be  found  in  published  form.  It  is 
the  practice  of  those  engaged  in  the  systematic  study  of 
plants  and  animals  to  record  accurately  the  description,  in 
some  recognized  scientific  periodical,  or  in  a  monograph,  of 
any  new  species  they  may  find.  When  such  is  done,  the 
one  who  names  and  describes  the  new  plant  affixes  thereto 
his  name,  in  full,  if  short,  but  usually  abbreviated.  In  some 
instances,  two  abbreviations  occur  after  a  scientific  name,  for 
example,  Echinochloa  crus-galli  (L.)  Beauv.  This  illustrates 
a  case  in  which  a  species  has  been  transferred  from  one 
genus  to  another.  Linnaeus  named  the  common  barnyard 
grass  Panicum  crus-galli  L.  In  his  revision,  Beauvois  trans- 
ferred the  common  barnyard  grass  to  the  genus  Echinochloa 
still  retaining  the  specific  name,  crus-galli.  Nomenclature 
rules  state  that  when  a  species  is  transferred  in  this  manner 
from  one  genus  to  another,  the  original  author  (in  this 
case,  Linnaeus)  must  always  be  cited  in  parenthesis,  fol- 
lowed by  the  author  (in  this  case,  Beauvois)  of  the  new 
binomial. 

Botanical  varieties  or  subspecies  are  often  printed  as 
trinomials,  for  example,  the  bush  variety  of  Phaseolus 
vulgaris  is  written  Phaseolus  vulgaris  nanus  or  Phaseolus 
vulgaris  var.  nanus.  Agricultural  "varieties"  are  desig- 
nated by  common  names,  for  example,  in  beans,  there  are 
such  varietal  names  as  Early  Bountiful,  Black  Valentine, 
Giant  Stringless,  Green-pod,  etc. 

Scientific  names  are  in  Latin.  This  is  probably  the  most 
universal  language,  which  fact  was  recognized  by  Linnaeus, 
and  hence  he  adopted  it  in  his  system  of  nomenclature.  The 
species  and  genus  agree  in  gender.  For  example,  Brassica 
rapa  (turnip) ,  Triticum  aestivum  (common  wheat) ,  and  Rubus 
villosus  (northern  dewberry). 


66  BOTANY  OF  CROP  PLANTS 

Descriptive  Nature  of  Specific  Names. — Specific  names 
are  commonly  descriptive.  They  may  be  descriptive  of 
(i)  some  plant  character  or  habit,  (2)  habitat,  or  (3)  dis- 
tribution; and,  in  some  instances  (4)  the  species  may  bear 
the  name  of  an  individual.  By  far  the  largest  proportion 
of  specific  names  is  descriptive  of  some  striking  habit  or 
character  of  the  plant.  For  example,  the  trailing  or  pro- 
cumbent Trifolium  (clover)  is  Trifolium  repens  (repens, 
creeping);  the  sweet  clover  with  white  flowers  is  Melilotus 
alba  (alba,  white);  the  narrow-leafed  crab-apple  is  Malus 
angustifolia  (angustus,  narrow — folium,  leaf). 

In  Vitis  Hparia,  the  streamside  grape,  riparia  is  descrip- 
tive of  this  species'  habitat.  The  common  black-cap  rasp- 
berry is  Rubus  occidentalis;  here  the  specific  name  means 
"western."  Again,  in  Vaccinium  canadense,  the  Canada 
blueberry,  the  specific  name  indicates  geographical  distribu- 
tion. The  systematist  frequently  uses  the  name  of  an  indi- 
vidual for  the  specific  name.  This  may  be  done  as  a  token 
of  friendship,  or  recognition  of  distinction,  or  to  indicate  the 
finder  of  the  new  form.  For  example,  Prunus  besseyi,  is 
after  the  well-known  botanist,  Charles  Bessey.  The  i 
ending  is  the  Latin  genitive,  signifying  "of  Bessey." 

Scientific  Name  versus  Common  Name. — There  are  dis- 
tinct advantages  connected  with  the  knowledge  and  use  of 
scientific  names.  Often  the  same  species  has  many  common 
names.  Again,  several  distinct  species  often  may  go  by  the 
same  common  name.  The  use  of  one  scientific  name  will  do 
away  with  much  misunderstanding  as  to  what  plant  is 
actually  referred  to. 

General  References 

Bailey,  L.  H.:  The  Standard  Cyclopedia  of  Horticulture.    The  Macmillan 

Co.,  1914. 
Baillon,  H,:  Histoire  des  plantes.    Paris,  1894. 


THE   CLASSIFICATION  AND   NAMING   OF  PLANTS  67 

Bentham,  G.,  and  Hooker,  J.  D.:  Genera  Plantarum.    London,  1862-1883. 
Brixton  and  Brown  :  An  Illustrated  Flora  of  the  Northern  States  and  Canada. 

Scribners,  New  York,  1913. 
Card,  Fred  W.:  Bush-fruits.     The  Macmillan  Co.,  1909. 
CoRBETT,  L.  C:  Garden  Farming.     Ginn  &  Co.,  1913. 
Coulter,  J.  M.,  Barnes,  C.  R.,  and  Cowles,  H.  C:  A  Textbook  of  Botany. 

American  Book  Co.,  1911. 
De  Candolle,  Alphonse:  The  Origin  of  Cultivated  Plants.     D.  Appleton 

&  Co.,  1892. 
Engler  and  Prantl:  Die  naturlichen  Pflanzenfamilien. 
HtJNT,  T.  F.:  Forage  and  Fiber  Crops  in  America.    Orange  Judd  Co.,  1908. 
Knuth,   Paul.:  Handbook  of  Flower  Pollination.    Translation  by  J.  R. 

Ainsworth  Davis.     Oxford,  Clarendon  Press,  1906. 
Montgomery,  E.  G.:  Productive  Farm  Crops.    Lippincott  Co.,  1916. 
Perclval,  John.:  Agricultural  Botany.    Henry  Holt  &  Co.,  1905. 
Piper,  Charles  V.:  Forage  Plants  and  Their  Culture.    The  Macmillan  Co., 

1914. 
Shepperd,  J.  H.:  Root  Systems  of  Field  Crops.    N.  D.  Agr.  Exp.  Sta.  Bull. 

64--  525-536,  1905- 
Strasburger,  E.,  Noll,  F.,  Schenck,  H.,  and  Schimper,  A.  F.  W.:  A  Text- 
book of  Botany.     Macmillan  Co.,  191 2. 
Ten  Eyck,  A.  M.:  The  Roots  of  Plants.    Kans.  Agr.  Exp.  Sta.  Bull.  127: 

199-252,  1904. 
ViLMORiN,  M.  M.:  The  Vegetable  Garden.    John  Murray,  London,  1905. 
WossiDLO,  Paul.!  Leitfaden  der  Botanik.     Berlin,   1911. 


PART  II 

CHAPTER  IX 
GRAMINE^   (POACE^),  GRASS  FAMILY 

No  family  of  plants  is  of  greater  economic  importance  than 
the  grass  family.  It  has  several  thousand  species,  among 
which  are  the  "grains"  (such  as  wheat,  oats,  barley,  corn, 
rice,  and  others)  and  the  meadow,  pasture  and  range  grasses. 
The  grasses  grown  for  "grain"  were  the  first  plants  to  be 
cultivated  by  the  human  race.  Members  of  this  family 
are  widely  distributed  over  the  surface  of  the  earth,  from 
tropical  to  polar  regions  and  from  low  to  very  high  altitudes. 
In  many  parts  of  the  world,  grasses  form  a  dominant  part 
of  the  plant  covering.  Examples  of  extensive  grass  associa- 
tions are  meadows,  steppes,  and  savannahs.  Meadows  are 
moist  grass  lands  and  may  occur  in  all  climates.  Steppes  are 
dry  grass  lands.  The  Old  World  steppes  of  Russia,  Hungary, 
Roumania,  and  Spain,  the  plains  of  the  Western  United 
States,  and  the  pampas  of  South  America  are  excellent 
examples.  Savannahs  are  dry  grass  lands  with  scattered 
trees.  The  best  examples  of  these  are  the  llanos  of  Venezuela, 
and  the  patanas  of  Ceylon. 

Habit  of  Plants.— Most  grasses  are  low,  erect  herbs.  A 
few,  such  as  the  bamboos,  are  shrubs  or  trees.  Bamboo 
has  a  woody  stem  which  may  reach  a  height  of  loo  feet  or 
more.  Some  grasses  are  trailing,  one  or  more  being  re- 
ported as  climbing  over  trees  loo'^feet  high.  Others,  like 
69 


70  BOTANY  OF  CROP  PLANTS 

rice  cut  grass  (Homalocenchrus)  are  feeble  climbers  or  support 
themselves  by  means  of  numerous  hooked  prickles  on  their 
leaves. 

Many  of  our  common  pasture  and  meadow  grasses,  and 
all  the  cereals,  complete  their  life  period  in  one  season.  Such 
plants  are  said  to  be  annual.  In  cool  climates,  certain 
grasses  behave  as  winter  annuals,  living  through  the  winter 
as  small  plants  and  sending  up  jQower  stalks  the  following 
spring.  So-called  "winter"  or  "fall  grasses"  behave  in  this 
manner.  A  number  of  grasses,  such  as  the  pernicious  quack 
grass  {Agropyron  re  pens),  lawn  grass  {Poa  pratensis),  and 
others,  are  perennial,  i.e.,  with  a  course  of  life  extending  over 
three  or  more  seasons. 

Roots. — The  root  system  of  grasses  is  fibrous,  that  is, 
composed  of  numerous  slender  roots  of  about  equal  diameter. 
No  grasses,  at  maturity,  possess  a  tap-root  system,  as  that 
of  radish,  dandelion,  beet,  and  others.  In  this  there  is  a 
strong  leading  central  root.  The  primary  roots,  those  that 
arise  directly  from  the  seed,  are  temporary,  dying  after  the 
permanent  roots  are  able  to  support  the  plant.  The  perma- 
nent roots  arise  from  that  portion  of  the  stem  which  ex- 
tends from  the  germinating  seed  to  the  surface  of  the  ground. 
These  roots  are  always  produced  at  about  the  same  distance 
below  the  surface,  regardless  of  the  depth  at  which  the  seed 
is  planted  (Fig.  3) . 

Grasses  are  classed  as  shallow-rooted  plants.  However, 
great  variation  has  been  observed  in  the  depth  to  which  the 
roots  penetrate,  some  extending  to  depths  which  cannot  be 
considered  as  shallow.  Roots  of  buffalo  grass  {Buchloe) 
sometimes  go  to  a  depth  of  7  feet.  Rye  roots  have  been 
found  penetrating  to  a  depth  of  3  feet,  corn  33^  feet  (Fig. 
56),  emmer  and  spelt  3}^  feet,  and  wheat  more  than  4  feet. 

Roots  may  break  through  the  sheaths  (that  part  of  the 


GRAMINE^   (pOACE^e),   GRASS  FAMILY  7 1 


Fig.  25. — Wheat  plant  showing  the  general  habit  of  grasses. 


72 


BOTANY  OF  CROP  PLANTS 


leaf  which  is  wrapped  about  the  stem)  of  the  first  few  leaves, 
or  spring  freely  from  underground  stems.  They  may  also 
arise  from  joints  above  the  ground  line,  as  in  corn.  If  such 
aerial  roots  reach  the  ground  they  may  serve  as  supporting 
or  "prop"  roots  (Fig.  56). 

Stems. — General   Characteristics. — The    stems   of   grasses 
are   called  culms.     They  are  cylindrical  (rarely  flattened), 

and  divided  into  sections 
{internodes)  (Fig.  25)  which 
are  usually  hollow,  but  some- 
times filled  with  pith,  as  in 
corn.  When  young,  the  in- 
ternodes are  soKd,  but,  as 
the  stem  enlarges,  the  central 
portion  is  ruptured  and  a 
hollow  is  formed.  The  nodes 
(Fig.  25),  the  enlarged  joints 
between  the  internodes,  are 
solid.  Enlargement  of  the 
nodes  is  due  partly  to  a 
thickening  of  the  leaf  base  at 
each  node  (Fig.  26)  and 
partly  to  enlargement  of  the 
stem  itself.  In  most  grasses, 
the  part  of  the  culm  within 
the  sheath  remains  soft  and 
continues  to  grow  or  retain 
the  power  of  growth  after  the  portion  not  in  the  sheath  has 
ceased  growth,  or  lost  the  ability  to  grow.  The  youngest 
part  of  each  internode  is  at  its  base,  surrounded  by  the  basal 
swelling  of  the  leaf  sheath  (Fig.  26).  Each  internode  has  its 
own  growing  zone. 
Lodging. — It  is  customary  to  speak  of  a  grass  as  "lodged" 


Fig.  26. — Barley.  A,  portion  of 
leaf  at  juncture  of  leaf  and  blade; 
B,  stem  cut  in  median  lengthwise 
section.      X  2}i. 


GRAMINE^   (pOACEiE),   GRASS   FAMILY  73 

when  its  stems  are  bent  over  and  caused  to  lie  on  the  ground 
by  the  mechanical  action  of  a  high  wind,  or  driving  rain. 
Some  grasses  lodge  more  easily  than  others.  This  may  be 
due  either  to  their  greater  height,  heavier  fruiting  head,  or 
to  a  lack  of  strengthening  material.  Moreover,  it  has  been 
shown  that  an  excessive  amount  of  available  nitrates  in  the 
soil  favors  lodging.  As  it  has  been  demonstrated  that  the 
application  of  nitrate  fertilizers  to  a  soil  tends  to  suppress 
the  amount  of  silicon  taken  in  by  the  wheat  plant,  the  greater 
frequency  of  lodging  of  plants  grown  on  such  a  soil  may  re- 
sult from  a  stem  weakness  caused  by  a  lack  of  silicon  within 
them.     However,  the  causes  of  lodging  are  not  well  known. 

The  stems  of  lodged  grain  are  not  necessarily  broken. 
The  reverse  is  the  case,  as  is  shown  by  the  fact  that  the  lodged 
culm  has  the  power  of  partially  or  entirely  erecting  itself. 
This  power  is  exhibited  more  strongly  in  growing  or  imma- 
ture culms  than  in  old  ones.  When  a  grass  stem  is  lodged, 
the  cells  on  the  lower  side  of  each  internode,  at  its  base, 
grow  more  rapidly  than  those  on  the  upper  side,  and,  hence, 
the  stem  curves  upward.  This  behavior  is  a  response  to 
the  stimulus  gravity.  The  manner  in  which  gravity  acts 
upon  an  organ  as  a  stimulus  has  not  been  demonstrated. 
However,  it  has  been  experimentally  determined  that  all 
plants  make  pronounced  adjustments  in  their  growth  in 
response  to  gravitation.     This  property  is  called  geotropism. 

Tillering. — It  is  a  common  observation  that  trees,  shrubs 
and  most  herbaceous  plants  produce  side  branches  in  regular 
order,  and  that  these  arise  at  the  nodes  along  the  stem.  The 
side  branches  of  the  grasses  are  not  so  obvious  as  those  in 
trees  and  shrubs,  for  example,  for  the  reason  that  the  culms 
of  most  grasses  produce  branches  from  the  lower  nodes  only. 
This  branching  in  grasses  is  known  as  "stooling,"  ''tillering," 
or  "  moo  ting. "    The  individual  branches  are  known  as ' '  tillers' ' 


74 


BOTANY   or   CROP   PLANTS 


(Fig.  27),  and  the  entire  mass  of  branches  is  the  "siv/ol." 
Common  cereals,  such  as  wheat  and  oats,  invariably  pro- 
duce a  number  of  tillers,  sometimes  as  many  as  50.  The 
tillers  from  the  primary  culm  may  produce  tillers  (lateral 
branches)  and  these  in  turn  other  tillers,  so  that  under  favor- 
able conditions  several  dozen  culms  may  result  from  a  single 
seed.     As  the  internodes  are  much  shortened,  the  branches 


-tertiary  stem 
6cale  leaf 
'^^^econdary  stem 
^  priivar\j  stem 

^^-^crown  roots 


-^rain  remains 
J^^nmar\j  roots 

-Diagrammatic  representation  of  tillering  in  cereals. 
{After  Schindler.) 

appear  to  come  out  at  one  point.  In  the  wheat  plant,  two 
or  three  weeks  old,  three  or  four  buds  may  be  found,  one  in 
the  axil  of  each  leaf.  Tillering  results  from  the  outgrowth 
of  these  lateral  buds. 

Tillering  activity  varies  with  the  species,  the  individual, 
and  environmental  conditions.  In-  general,  winter  grains 
tiller  more  than  summer  ones.  It  is  dependent  especially 
upon  the  depth  of  seeding.  There  seems  to  be  an  optimum 
depth,  which  varies  with  the  sort  of  grass.  The  average 
depth  of  the  tillering  node  in  cereals  is  about  i  to  2  centi- 


GRAMINE^  (POACE^),  GRASS  FAMILY 


75 


meters.  Tillers  are  produced  freely  in  moderately  warm, 
sandy  soil.  The  number  of  tillers  is  also  increased  by 
a  large  amount  of  reserve  material  in  the  seed,  and  by  high 
soil  fertility,  and  by  thin  seeding.  The  effect  of  this  last 
factor  is  well  shown  in  the  following  data  taken  from  the 
Nebraska  Experiment  Station  Bulletin  127: 

Tillering  of  Oats 


Pecks  of  seed  sown  per 
acre 

Stems  per  loo  plants 

Total  number  of  stems 
per  acre 

4 
8 

16 

466 
279 

140 

1,419,000 
1,732,000 
2,283,000 

The  production  of  tillers  in  the  small  grains  is  altogether 
desirable  from  the  farmer's  standpoint,  as  it  is  an  important 
factor  determining  yield. 

Bulbous  Grasses. — In  a  few  species  such  as  timothy 
(Phleum  pratense)  and  tall  oat  grass  (Arrhenatherum  elatius), 
some  of  the  lower,  short  internodes  are  enlarged  into  bulb- 
like bodies  containing  a  store  of  nourishment. 

Rhizome-bearing  Grasses. — Perennial  grasses  usually 
have  rhizomes  or  rootstocks,  horizontally  elongated  under- 
ground stems,  which  give  rise  to  erect  annual  stems  that 
bear  foliage  leaves  and  flowers.  These  underground  stems 
are  very  efficient  as  reproductive  organs,  for,  as  a  result  of 
their  elongation  in  the  soil,  the  plant  is  able  to  invade  areas 
already  occupied  by  other  plants.  Furthermore,  each  root- 
stock  is  capable  of  budding  a  new  plant  at  every  node,  and 
should  it  be  dragged  from  the  ground  by  cultivating  machin- 
ery and  broken  into  a  number  of  separate  pieces,  each  piece 
will  give  rise,  under  favorable  conditions,  to  a  new^plant. 
Quack  grass  (Agropyron  repens),  and  many  other  of  our 


76  BOTANY  OF  CROP  PLANTS 

worst  weeds,  owe  their  obnoxious  character  mainly  to  the 
possession  of  rootstocks.  Such  plants  are  not  dependent 
upon  seed  production  alone,  but  in  addition  spread  by  means 
of  their  rootstocks.  The  rootstock  is  a  storehouse  of  food 
material,  and  although  the  leaves  and  stems  above  ground 
may  be  destroyed,  new  shoots  are  sent  up  from  it,  drawing 
upon  the  stored  food  supply.  For  this  reason,  perennial 
weeds  of  all  kinds  are  difficult  to  eradicate.  Any  method  of 
elimination  adopted  is  based  upon  the  knowledge  that  the 
food  stored  in  the  underground  stems  is  made  in  the  green 
leaves;  therefore,  the  development  of  green  leaves  must  not 
be  allowed. 

Rhizomes  of  grasses  bear  brown  or  colorless  sheathing 
scales  (rudimentary  leaves)  containing  in  their  axils  active 
buds  which  may  develop  into  erect  stems.  Under  favorable 
conditions,  roots  are  produced  at  the  nodes  of  the  rhizomes. 
Grasses  possessing  rhizonies  are  rhizomatous. 

When  the  intemodes  of  the  rhizomes  are  very  short,  the 
culms  are  close  together,  and  the  grass  is  known  as  a  tufted 
grass  or  as  bunch  grass,  as  in  meadow  fescue  {Festuca  pra- 
tensis) .  Many  of  our  most  valued  range  grasses  have  the 
bunch  habit.  When  the  internodes  are  long,  the  culms  are 
more  widely  separated,  and  a  creeping  grass,  as  awnless 
brome  grass  (Bromus  inermis),  is  the  result. 

Stoloniferous  Grasses. — When  the  horizontal  stems  are  at 
or  above  the  surface  of  the  ground,  they  are  called  runners  or 
stolons,  as  in  buffalo  grass  {Buchloe  dactyloides) .  Outside  of 
the  grass  family,  the  runners  or  stolons  of  strawberry  are 
very  typical.  Stolons  are  about  as  effective  as  rhizomes  in 
propagation.  They  usually  produce  a  more  open,  loose  tuft. 
This  is  due  to  the  long  internodes.  Stoloniferous  grasses  do 
not  produce  as  solid  and  uniform  a  turf  as  most  rhizomatous 
grasses.     Neither  is  it  likely  that  the  former  would  produce  a 


GRAMINE^    (POACE^),   GRASS   FAMILY  77 

sod  that  would  be  as  enduring  under  conditions  affecting  the 
sod  surface,  such  as  heavy  trampling  or  close  grazing. 

Leaves. — General  Characteristics. — In  grasses,  a  single  leaf 
arises  at  each  node.  Leaves  disposed  in  this  fashion  along  a 
stem  are  said  to  be  alternate.  If  one  starts  with  a  certain 
leaf,  the  leaf  next  above  or  next  below,  is  on  the  opposite  side 
of  the  stem,  i8o°  around  the  circumference.  This  arrange- 
ment gives  two  vertical  rows  of  leaves  opposite  each  other 
on  the  stem.  Such  an  arrangement  is  said  to  be  two-ranked, 
distichous,  or  one-half  spiral.  We  shall  have  occasion  further 
on  to  discuss  other  leaf  arrangements,  and  to  emphasize 
the  fact  that  leaves  are  developed  on  a  stem  in  a  definite 
order. 

The  grass  leaf  in  general  appearance  is  unlike  that  of  such 
common  plants  as  apple,  cottonwood,  maple  and  beet.  In 
these  the  leaf  has  a  definite,  narrow  stalk  or  petiole  and  an 
expanded  blade  (Fig.  159).  The  grass  leaf  is  divided  into 
two  distinct  parts,  sheath  and  hlade  (Fig.  26).  The  sheath 
represents  the  leaf  base,  and  forms  a  tube  around  the  culm. 
At  the  base  of  the  leaf  sheath,  there  is  a  distinct  swelling. 
The  more  or  less  flattened  part  of  the  leaf  which  spreads 
away  from  the  culm  is  the  hlade  (lamina).  The  blades 
are  parallel- veined,  that  is,  have  many  veins,  about  equal 
in  size,  running  parallel,  and  joined  by  inconspicuous  vein- 
lets.  Parallel  venation  is  characteristic  of  the  leaves  of 
grasses,  sedges,  rushes,  lilies  and  most  all  other  monocoty- 
ledonous  plants. 

Growth  of  Leaves. — In  the  early  life  of  the  grass  plant, 
leaves  grow  faster  than  internodes.  This  results  in  a  tuft 
of  leaves.  Some  leaves  elongate  indefinitely.  The  tip  of 
the  leaf  blade  is  the  oldest  portion.  The  growing  point  is 
at  the  base  of  the  blade.  This  growing  zone,  as  a  rule,  is 
marked  by  a  whitish  or  light  green  semicircle  (Fig.  26). 


yg  BOTANY  OF  CROP  PLANTS 

The  upper  portion  of  the  leaf  may  therefore  be  removed 
without  permanent  injury  to  the  plant.  This  is  well  shown 
in  the  rapid  recovery  of  the  leaves  of  lawn  grass  after  mowing, 
and  of  pasture  grasses  after  grazing. 

Scales  and  Bracts. — Reduced  leaves  in  the  form  of  scales 
and  bracts  occur  in  grasses.  Such  reduced  leaves  are  termed 
''scales"  when  they  appear  lower  on  the  stem  than  the 
foliage  leaves,  and  "bracts"  when  higher.  For  example, 
the  reduced  leaves  at  tillering  nodes  are  "scales"  (Fig. 
27),  while  the  reduced  leaves  (glumes)  in  the  inflorescence 
are  "bracts"  (Fig.  28).  Scales  and  bracts  seldom  possess 
chlorophyll  (green  coloring  material  in  plants),  and,  hence, 
are  incapable  of  carrying  on  synthesis  of  carbohydrates. 
The  scales  and  bracts  in  grasses  have  the  same  one-half 
spiral  arrangement  as  the  foliage  leaves  and  although  they 
may  be  very  close  together  on  the  axis,  careful  observation 
shows  them  to  have  this  typical  arrangement  of  all  grass 
leaves. 

Ligule. — At  the  junction  of  the  sheath  and  blade  is  a 
membranous  or  cartilaginous  ring  or  fringe,  the  ligule  (Fig. 
26).  It  is  next  to  the  culm,  and  varies  in  size,  shape,  and 
hairiness  in  different  species  of  grasses.  The  ligule  is 
sometimes  absent. 

Auricle  (Fig.  26). — This  is  a  more  or  less  pointed,  thin, 
ear-like  structure  projecting  from  the  leaf  edge  at  the  junc- 
tion of  sheath  and  blade.  It  often  clasps  the  stem  but 
may  be  more  or  less  twisted  and  bent  away  from  it.  It 
varies  greatly  in  size  and  shape.  In  the  tribe  Hordeae, 
the  auricles  are  characteristic.  They  are  entirely  absent 
in  some  species. 

Inflorescence. — The  grass  [inflorescence  (flower  cluster) 
consists  of  a  number  of  groups  of  flowers,  each  group  being 
called  a  spikelet.    The  spikelet  is,  in  fact,  the  unit  of  the 


GRAMINE^   (POACE^),    GRASS   FAMILY 


79 


lemmas 


grass    inflorescence.     The    spikelets    are    attached    either 
directly  or  indirectly  to  a  main  axis,  the  rachis  (Fig.  28). 

The  three  common  sorts  of  grass  inflorescences  are  the 
spike,  panicle,  and  raceme.  When  the  rachis  is  unbrahched, 
so  that  the  spikelets  are  not  borne  on  individual  stalks,  but 
are  attached  directly  (sessile)  to  the  rachis,  the  result  is  a 
spike.  The  inflorescences  of  wheat, 
barley,  and  rye  are  good  examples  of 
spikes.  Usually,  each  culm  bears  a 
single  spike.  In  the  raceme,  each  spike- 
let  is  borne  on  a  short  branch  of  the 
rachis,  as  in  sheep's  fescue  {Festuca 
ovina).  In  the  panicle,  the  primary 
branches  of  the  rachis  branch  one  or 
more  times  (Fig.  44).  These  branches 
may  be  long  and  widely  spreading,  as 
in  oats  and  brome  grass,  or  short  and 
rather  appressed  to  the  rachis,  as  in 
timothy,  meadow  foxtail  {Alopecurus) , 
and  Koeleria. 

Different  types  of  inflorescences  be- 
sides the  spike,  raceme  and  panicle  will 
be  met  with  in  some  of  the  following 
families.  We  shall  also  see  that  these 
three  types  are  not  confined  to  the  grass  family,  but  are  in 
fact  exceedingly  common  among  seed  plants  of  all  kinds. 

Spikelet. — The  spikelet  is  the  unit  of  inflorescence  in 
grasses.  A  typical  spikelet,  such  as  that  of  oats  (Fig.  46), 
or  wheat  (Fig.  28),  for  example,  consists  of  a  shortened  axis, 
the  rachilla,  bearing  a  number  of  chaff-like,  two-ranked 
(distichous),  overlapping  bracts  (glumes  of  some  authors). 
The  two  lowermost  bracts  are  empty,  that  is,  do  not  bear 
flowers  in  their  axils.     Fig.  29  shows  a   dissected   wheat 


rachis 


Fig.  28. — Single  spike- 
let of  common  wheat 
(Triticumaestiviim).  X  2. 


8o 


BOTANY   OF   CROP   PLANTS 


spikelet  with  its  parts  removed  in  order.  Each  spikelet  is 
subtended  by  these  two  empty  bracts.  Following  the  sug- 
gestion of  Piper,  we  shall  designate  these  two  basal,  empty 
bracts  as  "glumes."  The  lower  of  these  is  the  "first  glume," 
the  upper  the  "second  glume."  Above  the  two  glunies,  on 
the  rachilla,  are  one  or  more  bracts;  each  one  of  these  is 
known  as  a  lemma  (flowering  glume  and  inferior  palea  of 
some  authors).  Normally,  there  is  a  flower  in  the  axil  of 
each  lemma.  Opposite  each  lemma  is  a  two-nerved,  two- 
keeled,  bract-like  structure,  the  palet  (the  palea,  prophyllum, 


Iji  glume 


Fig.  29. — Spikelet  of  common  wheat  (Triticum  sestivum)  dissected,  the  parts 
removed  in  order. 


bracteole,  and  superior  palea  of  some  authors) .  Its  back  is 
turned  toward  the  rachilla.  It  frequently  envelops  the 
other  parts  of  the  flower  with  its  infolded  edges.  The  palet 
is  never  awned  (bearded).  While  the  glumes  and  lemmas 
are  inserted  on  the  rachilla,  the  palet  is  inserted  on  a  very 
short  flower  stalk  (pedicel) .  At  the  base  of  the  ovary,  on  the 
side  opposite  the  palet,  are  two  minute  scales,  the  (anterior) 
lodicules  (Fig.  30).  Inside  the  palet,  and  placed  farther  up 
on  the  flower  stalk,  are  three  stamens  and  a  single  pistil. 
Thus  we  see  that  in  the  typical  spikelet  there  are  two  glumes 


GRAMINE^   (POACE^),   GRASS   FAMILY 


8l 


subtending  one  or  more  lemmas;  in  the  axil  of  each  lemma  is 
a  flower,  and  each  flower  consists  of  a  palet  (outer  perianth), 
two  lodicules  (inner  perianth),  three  stamens,  and  a  single 
pistil.  Each  stamen  has  a  large  anther.  The  filament 
{stalk)  is  attached  at  the  base  of  the  anther,  but  on  account 


Fig.  30. — Wheat  flower  with  lemma  removed;  considerably  magnified. 


of  the  extreme  sagittate  nature  of  the  latter,  it  appears 
versatile.  The  ovary  is  one-celled,  one-seeded,  bears  two 
styles  and  two  feathery  stigmas. 

There  are  many  deviations  from  the  typical  form  of  spikelet.  In  Colean- 
Ihus,  the  empty  glumes  are  absent;  in  Nardus,  solitary;  in  Bomalocenchrus, 
mere  rudiments.  In  some  Agrostis  species,  the  palet  is  rudimentary.  It  is 
not  always  two-keeled,  but  generally  two-nerved.  There  is  a  third  (posterior) 
lodicule  in  some  grasses.  Although  the  stamens  are  as  a  rule  three,  there  are 
six  in  most  bamboos  and  in  rice  {Oryza).  In  Streptochceta  and  Oryza  (oc- 
casionally), there  are  three  styles,  and  only  one  in  Nardus. 
6 


82  BOTANY  OF  CROP  PLANTS 

The  awns  or  beards  are  brittle-like  structures  on  lemmas  or 
glumes,  usually  on  the  former.  They  are  commonly  termi- 
nal, as  in  wheat,  or  dorsal  (attached  to  back  of  lemma),  as 
in  oats.  Zoebel  and  Mikosch,  working  with  two-rowed  and 
six-rowed  barleys,  arrived  at  the  conclusion  that  awns  are 
transpiring  (water-losing)  organs.  They  noted  that  bearded 
barley  spikelets  transpired  more  than  artificially  beardless 
ones  of  the  same  sort  under  similar  conditions.  They  also 
observed  that,  at  the  time  of  kernel  development,  transpira- 
tion from  the  spikelet  was  most  intense,  probably  corre- 
sponding to  the  time  of  greatest  movement  of  reserve  ma- 
terial to  the  kernel. 

Up  to  1906,  Hackel  reports  67  species  of  cleistogamous 
grasses.  As  compared  with  flowers  that  open,  cleistogam- 
ous ones  generally  have  reduced  lodicules,  smaller  anthers, 
a  shorter  pistil,  and  less  pollen.  In  a  few  cases  {Panicum 
clandestinum)  for  example,  -claasmogamous  spikelets  and 
cleistogamous  spikelets  may  occur  in  the  same  inflorescence. 
According  to  Koernicke,  two-rowed  erect-eared  barley 
{Hordeum  distichon  erectum)  bears  only  cleistogamous 
flowers. 

Pollination. — Wind  is  the  chief  agent  in  the  dissemination 
of  grass  pollen.  In  all  grasses  the  pollen  is  light  and  dry,  and 
hence  easily  blown.  Insects  play  a  very  unimportant  part 
in  this  process. 

Most  grass  flowers  open  to  shed  their  pollen,  that  is  show 
chasmogamy.  In  some  grasses,  however,  the  glumes  do  not 
spread  apart,  thus  allowing  the  stamens  and  pistils  to  be- 
come exposed.  Flowers  that  do  not  open  are  said  to  show 
deistogamy. 

Fruit. — In  all  grasses,  the  fruit  is  one-seeded,  dry,  and  does 
not  spUt  open  at  maturity  to  allow  the  seed  to  escape.  The 
pericarp  (ovary  wall)  is  firmly  attached  to  the  seed  coat. 


GRAMINE^  (pOACEiE),  GRASS  FAMILY 


83 


The  grass  fruit  is  called  a  grain  or  caryopsis.  There  is  an 
abundance  of  starchy  endosperm.  Sometimes  the  grain  is 
closely  adherent  to  the  palet  and  lemma,  as  in  most  barleys 
and  oats. 

Phylogeny  of  Grasses. — The  history 
of  the  evolution  of  a  group  of  organ- 
isms is  phylogeny.  What  is  the  origin 
of  the  grasses?  Are  they  primitive 
forms,  the  progenitors  of  such  closely 
related  groups  as  the  lilies  and  other 
common  monocotyledonous  plants;  or 
are  they  a  reduced  group?  By  those 
who  hold  the  latter  view,  which  is 
more  widely  accepted,  grasses  are  con- 
sidered to  have  come  from  Hly-Hke 
plants  by  a  reduction  and  modification 
of  a  number  of  part's  of  the  flower. 
Examination  of  the  floral  diagram  of  a 
typical  Hly  flower  is  shown  in  Fig.  31. 
It  has  two  sets  of  floral  segments  (which 
together  constitute  the  perianth)  which 
alternate,  two  whorls  of  stamens,  three 
in  each  whorl,  and  a  pistil  divided  into 
three  chambers,  hence  tri-carpellary. 
The  stamens  of  one  whorl  alternate  with 
those  in  the  other;  those  of  the  outer 
whorl  alternate  with  the  inner  segments 
of  the  perianth.  The  three  carpels 
alternate  with  the  inner  stamens.  In 
Fig.  31  is  shown  the  floral  diagram  of 
a  grass  flower  with  the  rudimentary  or 
missing  parts  shaded.  According  to  the  view  that  grasses 
are  reduced  Hhes;  there  was  a  reduction  in  the  lobes  of 


Fig.  31. — Diagram  of 
A  lily  flower,  and  B 
grass  flower  showing 
homologous  structures. 
A,  f,  bract;  ax,  axis; 
op,  outer  perianth;  ip, 
inner  perianth;  s,  sta- 
mens; c,  tricarpellary 
ovary.  B,  shaded  struc- 
tures are  aborted;  le, 
lemma  (bract) ;  ax,  axis; 
p  and  p',  palet  (outer 
perianth);  I  and  I', 
lodicules  (inner  peri- 
anth); 5  and  s',  two 
whorls  of  stamens;  c, 
tricarpellary  ovary.  {B 
after  Schuster.) 


84  BOTANY  OF  CROP  PLANTS 

the  pistil  from  three  to  one,  a  loss  of  one  whorl  of  stamens, 
and  a  reduction  in  the  number  of  perianth  lobes. 

Although  commonly  assumed  to  be  one-carpelled,  the 
grass  pistil  is  really  tri-carpellary.  This  latter  view  is 
held  by  a  number  of  morphologists  (Doell  and  Goebel), 
and  recently  has  been  quite  conclusively  demonstrated 
by  Walker  and  Schuster.  In  all  grasses,  the  pistil  has 
three  fibro-vascular  bundles.  Two  of  these  extend  to  the 
style  branches  and  the  third  (dorsal)  extends  to  the 
dorsal  lobe  of  the  pistil  or  to  the  third  rudimentary  style 
branch,  when  present.  This  third  bundle  bears  the  ovule. 
In  Streptochceta  and  Bambusce,  there  are  three  styles. 
Furthermore,  it  should  be  noted  that  the  three  vascular 
bundles  stand  in  regular  alternation  with  the  second  whorl  of 
stamens  and  the  inner  whorl  of  the  perianth. 

Rowlee,  in  a  study  of  Arundinaria,  a  bamboo,  concluded 
that  the  lodicules  represent  the  inner  perianth  whorl.  The 
common  view,  as  presented  by  Hackel,  has  been  that  lodi- 
cules are  bracts.  Schuster's  researches  substantiate  those 
of  Rowlee.  He  finds  that,  although  two  lodicules  is  the  com- 
mon number,  a  third  (anterior)  one  occasionally  occurs  (in 
Bambusae) ;  that  the  two  (posterior)  lodicules  are  not  bound 
together  at  first  but  originate  separately;  that  in  one  grass 
genus  {Streptochaeta) ,  at  least,  the  three  lodicules  are  inde- 
pendent. From  these  studies,  it  appears  that  the  lodicules, 
morphologically,  are  to  be  considered  as  the  inner  perianth 
whorl.  The  same  worker  (Schuster)  considers  the  palet  to 
represent  the  outer  perianth  whorl  of  this  lily-like  flower. 
The  palet  is  usually  two-keeled  or  two-nerved.  There  are 
cases  in  which  the  palet  is  divided  into  two  parts,  and  in 
which  there  is  a  third  part  in  a  rudimentary  condition.  In 
the  majority  of  grasses,  the  two  parts  of  the  palet  arise  from 
separate  primordia,  later  growing  together  to  form  a  single 


GRAMINE^  (POACE^),  GRASS  FAMILY         85 

structure;  the  third,  outer  perianth  whorl  aborts.  In  this 
connection  it  should  be  noted  that  the  palet  of  einkorn 
(Triiicum  monococcum)  divides  into  two  parts,  at  maturity, 
on  the  median  liiie,  each  half  bearing  a  keel  (Fig.  37). 

According  to  the  view  presented  above,  the  grass  spike- 
let  is  interpreted  as  a  modified  branch,  bearing  a  number 
of  distichous  bracts.  The  two  lower  bracts  (glumes)  are 
sterile.  The  flowers  occur  in  the  axils  of  the  lemmas.  The 
flower  is  of  the  lily  type.  The  outer  perianth  whorl  is  rep- 
resented by  the  palet,  the  inner  by  the  lodicules ;  one  whorl 
(inner)  of  stamens  (usually,  not  always)  is  aborted;  the  pistil 
is  three-carpelled.  Hence,  we  see  that  grasses  are  derivates 
of  a  normal  monocot  flower. 

Grass-like  Plants. — Grasses  are  closely  related  to  the 
sedges  {CyperacecB).  Sedges,  however,  have  solid  stems, 
usually  three-angled,  leaves  with  closed  sheaths,  and  the 
fruit  an  achene.  In  the  achene  the  pericarp  or  mature  ovary 
wall  is  not  firmly  grown  to  the  seed  coat  which  immediately 
adjoins  on  its  inner  surface.  The  achene  and  the  grain  are 
both  dry,  one-seeded  fruits  that  do  not  spht  (dehisce)  at 
maturity,  but  in  the  grain  the  mature  ovary  wall  is  closely 
adherent  to  the  seed  coat.  In  grasses,  as  pointed  out  on 
page  77,  the  leaves  are  two-ranked  or  distichous.  In 
sedges,  however,  the  leaves  are  three-ranked,  or  one-third 
alternate.  Sedges  grow  in  wetter  situations  than  grasses 
and  are  often  harsher  in  texture,  due  to  the  deposition  of 
silica  in  the  stems  and  leaves.  There  are  certain  rushes 
{JuncacecB},  other  than  rush-like  sedges,  which  are  grass- 
like in  appearance.  These,  however,  are  distinguished  from 
the  grasses  by  the  presence  of  a  perianth  of  six  distinct  glume- 
like segments. 


86  BOTANY  OF  CROP  PLANTS 


References 


Baillon,    H.;  L' evolution    de    Tinflorescence    dans    les    Graminees.     Bui. 

Soc.  Linn.  Nord,  France,  1894,  1123-1128. 
Bruns,  E.:  Der  Grasembryo.     Flora,  76:  1-33,  1892. 
Chase,  Agnes:  Notes  on  the  Cleistogamy  of  Grasses.     Bot.  Gaz.,  45:  135- 

136,  1908. 
DoELL.:  Untersuchungen  iiber  den  Bau  der  Grasblute.    Jahresber.  Mann, 

Ver.  f.  Naturk.,  1868,  xxxiv  and  1870,  xxxvi. 
GoEBEL,    K.:    Ein    Beitrag   zur   Morphologie   der    Graser.    Flora,    1895, 

Erganzungsband. 
GuERiN,  P.:  Recherches  sur  le  development   du  tegument  seminal  et  du 

pericarpe  des  graminees.     Ann.  Sci.  Nat.  Bot.,  9:  1-59,  1899. 
Hackel,  E.:  tJber  das  Aufbluhen  der  Graser.     Bot.  Ztg.,  33:  432,  1880. 

Untersuchungen  iiber  die  Lodiculas  der  Graser.    Engler's  Jahrb.,  i :  336- 

361,  1881. 

The  true  grasses.*  Transl.  from  German  by  F.  L.  Scribner  and  E.  A. 

Southworth.    Henry  Holt  &  Co.,  New  York,  1890. 

Uber  Kleistogamie  bei  den  Grasern.    Osterr.  Bot.  Ztschr.,  55:  81-88, 

143-154,  180-186,  1906. 
Hitchcock,  A.  S. :  A  Text-book  of  Grasses  with  Especial  Reference  to  the 

Economic  Species  of  the  Unites  States.    The  Macmillan  Co.,  New  York, 

1914. 
JUMELLE,  Henri.  :  Note  sur  la  constitution  du  fruit  des  Graminees.     Compt. 

Rend.  Acad.  Sci.  (Paris),  107:  285,  1888. 
Kennedy,  P.  B.:  The  Structure  of  the  Caryopsis  of  Grasses  with  Reference 

to  Their  Morphology  and  Classification.     U.S.  Dept.  Agr.,  Div.  Agros., 

Bui.  19,  1900. 
Lamb,  William  H.:  The  Phylogeny  of  Grasses.    Plant  World,  15:  264-270, 

1912. 
Piper,  C:  The  Terminology  of  the  Parts  of  the  Grass  Spikelet.    Science, 

n.  s.,  23:  789-790,  1906. 
RowLEE,  W.  W.:  The  Morphological  Significance  of  the  Lodicules  of  Grasses. 

Bot.  Gaz.,  25:  199-203,  1898. 
Schuster,  Julius:  tJber  die  Morphologie  der  Grasbliite.     Flora,  100:  213- 

266,  1910. 
Walker,  E.  R..:  On  the  Structure  of  the  Pistils  of  Some  Grasses.    Thesis, 

Univ.  Nebr.,  1906. 
Ward,  H.    Marshall:  Grasses,  a  Handbook   for  Use  in  the  Field  and 

Laboratory.     Cambridge,  1901. 
True,  Rodney:  On  the  Development  of  the   Caryopsis.    Bot.   Gaz.,  18: 

212-226,  1893  (contains  bibliography  on  development  of  grain). 


GRAMINE^  (POACE^),  GRASS  FAMILY        87 
CEREALS 

Cereals  are  those  grasses  which  are  grown  for  their  grain. 
Buckwheat  is  sometimes  considered  a  cereal  because  its 
fruit  (achene)  is  ground  into  flour,  but  it  is  not  so  considered 
here. 

Buckwheat,  flax,  and  others,  which  are  often  raised  for 
their  seed  or  fruit,  but  are  not  grasses,  are  discussed  wherever 
they  happen  to  come  in  the  botanical  order  of  treatment 
followed  here. 

Key  to  Groups  (Genera)  of  Important  Cereals^    . 

1  Whai  is  a  "key,"  and  how  is  it  used?  Throughout  the  following  pages 
there  will  be  a  number  of  "keys."  A  "key"  is  a  convenient  form  for  dis- 
tinguishing one  plant  from  another,  or  one  plant  group  from  another.  It 
presents  in  concise  form  the  principal  differences  between  the  plants  con- 
sidered. It  also  enables  one  to  determine  the  proper  classification  of  an 
unknown  plant.  Most  of  the  "keys"  in  the  following  pages  are  "artificial," 
that  is,  the  characters  used  are  obvious  ones.  The  "keys"  herein  are  con- 
structed on  the  dichotomous  plan,  i.e.  by  twos.  The  entire  number  of  groups 
under  consideration,  whether  these  be  species,  genera,  families,  or  higher 
divisions,  is  first  divided  into  two  subgroups;  each  of  the  subgroups  is  sub- 
divided into  two  groups,  and  so  on.  The  alternatives  are  equally  indented 
on  the  page.  In  the  key  to  the  genera  of  cereals,  they  are  first  divided  into 
two  large  groups,  the  first  including  Zea,  Oryza,  Andropogon  and  Millets; 
and  the  second,  Avena,  Secale,  Triticum  and  Hordeum.  It  is  seen  that  those 
genera  of  the  first  group  have  "spikelets  falling  from  the  inflorescence  entire 
..."  while  those  of  the  second  group  have  "spikelets  falling  from  the  in- 
florescence without  the  glumes.  .  .  "  Each  of  the  two  large  groups 
is  again  separated  into  two  subdivisions.  For  example,  the  genera  Avena, 
Secale,  Triticum  and  Hordeum,  are  subdivided  on  the  basis  of  their  inflores- 
cences. Avena  has  a  panicle  inflorescence,  while  Secale,  Triticum,  and  Hor- 
deum have  a  spike  inflorescence. 

Let  us  suppose  that  we  have  a  cereal  in  hand,  the  genus  of  which  we  wish 
to  determine.  First  of  all,  it  would  be  necessary  to  decide  whether  the 
"spikelets  fall  from  the  inflorescences  entire  .  .  .  ;"  or  "spikelets  fall 
from  the  inflorescence  without  the  glumes  .  .  .  ;"  if  it  has  the  characters 
of  the  second  alternative,  we  know  it  is  either  oats,  rye,  wheat  or  barley. 
Should  the  specimen  in  hand  have  a  spike  inflorescence,  oats  is  eliminated 
from  consideration,  and  the  plant  must  be  either  rye,  wheat  or  barley.    If, 


88  BOTANY  OF  CROP  PLANTS 

by  examination  of  this  unknown  plant,  we  find  now  that  there  are  "three 
spikelets  at  each  joint  of  the  rachis,"  it  must  belong  to  the  genus  Hordeum 
(barley). 

The  "key"  shows  many  of  the  characteristics  of  a  group.  Consider 
Triticum  (wheat),  for  example.  One  can  see  by  the  key  that  "spikelets  fall 
from  the  inflorescence  without  the  glumes,  which  remain  attached  to  the 
rachilla;  spikelets  one-many- flowered;  rachilla  often  produced  beyond  the 
upper  glume;  grain  with  a  longitudinal  furrow;  tuft  of  hairs  at  tip  of  ovary." 
Furthermore,  that  the  "inflorescence  is  a  spike";  that  there  is  "one  spikelet 
at  each  joint  of  the  rachis,"  and  the  "glumes  are  not  bristle-like,  but  broad," 

Spikelets  falling  from  the  inflorescence  entire  (glumes  attached  to  grain),  one- 
flowered,  or  if  two-flowered  the  lower  one  staminate;  rachilla  not  pro- 
duced beyond  the  flowers;  grain  without  a  longitudinal  furrow;  no  tuft 
of  hairs  at  tip  of  ovary. 
Flowers  staminate  and  pistillate;  borne  in  separate  inflorescences  on  the 

same  plant,  i.e.,  monoecious  (Fig.  57),  Zea  (maize  or  Indian  corn). 
Flowers  perfect  or  staminate;  when  the  staminate  are  present,  borne  in 
same  inflorescence  with  perfect. 
Spikelets  much  compressed  laterally  (Fig.  75),  Oryza  (rice). 
Spikelets  cylindrical  or  somewhat  compressed  dorsally. 
Lemma  and  palet  thin  and  papery,  much  more  delicate  in  texture  than 
the  empty  glumes  (Fig.   71),  Andropogon  (sorghum,  milo,  broom 
corn,  etc.) 
Lemma  and  palet,  at  least  of  perfect  flower,  never  thin  and  papery, 
parchment-like  or  leathery,  hard  and  shiny,  very  different  in  color 
and  appearance  from  the  glumes  (Fig.  83),  Chatochloa,  Echinochloa, 
Panicum,  Pennisetum  (millets). 
Spikelets  falling  from  the  inflorescence  without  the  glumes,  which  remain 
attached  to  the  rachilla;  spikelets  one  to  many-flowered;  rachilla  often 
produced  beyond  the  upper  glume  (Fig.  47) ;  grain  with  a  longitudinal 
furrow  (Fig.  34);  tuft  of  hairs  at  tip  of  ovary  (Fig.  34). 
Inflorescence  a  panicle  (Fig.  45),  Avena  (oats). 
Inflorescence  a  spike. 
One  spikelet  at  each  joint  of  rachis. 

Glumes  bristle-like  (Fig.  55),  Secale  (rye). 
Glumes  not  bristle-like,  broad  (Fig.  28),  Triticum  (wheat). 
Three  spikelets  at  each  joint  of  rachis  (Fig  49),  Hordeum  (barley). 

■  Key  to  Small-grain  Seedlings^ 

iThis  key  is  taken  verbatim  from  Carrier.  The  "collar"  is  a  narrow 
band,  usually  of  different  color  from  the  sheath  and  blade,  at  the  junction  of 
leaf  and  blade.    The  "claw-like  appendages"  are  the  auricles. 


GRAMINE^  (pOACEiE),  GRASS  FAMILY         89 

Collar  without  claw-like  appendages,  Oats  {Avena  saliva). 
Collar  with  claw-like  appendages  which  clasp  the  stem  more  or  less. 
Claws  hairy. 
Sheaths  and  blades  finely  pubescent,  soft,  and  velvety,  Emmer  {Triti- 

cum  dicoccum) . 
Sheaths  and  blades  not  pubescent. 

Collar  and  claws  large,  Spelt  {TrUicunt  spelta). 
Collar  and  claws  slender.  Wheat  {Triticum  astivum). 
Claws  not  hairy. 
Collar  and  claws  large  and  prominent. 
Nerves  of  blades  not  prominent,  upper  surface  rough,  Barley  {Uor- 

deum  sativum). 
Nerves  of  blades  broad  and  prominent,  smooth  on  upper  surface, 
Polish  wheat  (Triticum  polonicum). 
Collar  and  claws  slender. 
Blades  and  sheaths  sparsely  hairy.  Rye  {Secale  cereale). 
Blades  and  sheaths  free  from  hairs.  Durum  wheat  {Triticum  durum). 

References 

Aaronsohn,  a.:  tJber  die  in  Palastina  und  Syrien  wildwachsend  aufgefun- 
denen   Getreide-arten.     Verhandl.    K.    K.     Zool.    Bot.    Gesell.   Wien., 

59:385-590,  1909- 
Contribution  i  I'histoire  des  cereales.     Bui.  Soc.  Bot.  (France),  1909. 

Attekberg,  a.:  Die  Nachreife  des  Getreides.    Landw.  Versuchstat.,  67: 
129-143,  1907. 

Carleton,  M.  a.:  The  Small  Grains.     The  Macmillan  Co.,  1916. 

Carrier,  Lyman:  The  Identification  of  Grasses  by  Their  Vegetative  Char- 
acters.    U.  S.  Dept.  Agr.  Bull.  461:  1-30,  1917. 

Deherain  und  Dupont:  tJber  den  Ursprung  der  Starke  im  Getreidekorn. 
Comp.  Rend.  Acad.  Sci.  (Paris),  133:774,  1902. 

Desriot,  a.:  Les  cereales,  2  ed.,  Paris,  1910,  Hachette  et  cie. 

Ekkert,  F.:  tJber  Keimung,  Bestockung  und  Bewurzelung  der  Getreide- 
arten.     Inaug.  Diss.  Leipzig,  1873. 

Fruwirth,  C:  Das  Bliihen  des  Getreides.     Jahrb.  Deut.  Landw.  Gesell., 
22:  68-75,  1907- 

Fruwirth,    W.:  Die    Ziichtung    der    landwirtschaftlichen    Kulturpflanzen. 
Berlin,  1910. 

KoERNiCKE,   F.  and  Werner,  H.:  Handbuch  des  Getreidesbaues.     I.  Die 
Arten  und  Varietaten  des  Getreides.     II.  Die  Sorten  und  der  Anbau 
des  Getreides.     Berlin,  1885. 
tJber    die   Entstehung    und    das    Verhalten    neuer    Getreidevarietaten. 
Archivs  fiir  Biontologie,  1908. 


90  BOTAN"i^  OF   CROP  PLANTS 

Kraus,  C:  Die  Lagerung  der  Getreide.     Stuttgart,  1908. 

Knissling,  L.:  Untersuchungen  iiber  die  Keimung  der  Getreide.    Landw. 

Jahrb.  (Bayern),  1:449-514,  191 1. 
KuDELKA,  F.:  Uber  die  Entwicklung  und  den  Bau  der  Frucht  und  Samen- 

schale  unserer  Cerealien.    Landw.  Jahrb.,  4:  461-478,  1875. 
HiTiER,  H.:  Les  cereales  secondaires.     Seigle,  Mais,  Sarasin,  Millet,  Rhiz 

Paris,  19 10. 
Hoffman:  Das  Getreidekorn.     Berlin,  191 2. 

HxJNT,  T.  F.:  The  Cereals  of  America.     Orange  Judd  Co.,  New  York,  1905. 
NowACKi,  A.:  Anleitung  zum  Getreidebau,  IV.     Berlin,  1905. 
RiMPAU,  W.:  Das  Bliihen  des  Getreides.    Landw.  Jahrb.,  1882   (contains 

the  old  literature  on  the  blooming  of  grasses). 
Untersuchungen  iiber   die   Bestockungen   des   Getreides.     Jahrb.    Deut. 

Landw.  Gesell.,  1903. 
ScHiNDLER,  Franz:  Der  Getreidebau.     Berlin,  1909. 
ScHMiD,  B.:  Bau  und  Funktionen  der  Grannen  unserer  Getreide-arten.     Bot. 

Centralbl.,  76,  1898. 
Schmidt,  O.:  Uber  den  Entwicklungverlauf  beim  Getreide.    Ein  Beitrag 

zur  Sortenkenntnis.    Landw.  Jahrb.,  45:  267-324,  1913. 
ScHULz,  A.:  Die  Geschichte  der  kultivierten  Getreide,  I.     Halle,  1913. 
ScHULz,  B.:  Wurzelatlas.     Darstellung  natUrlicher  Wurzelbilder  der  Halm- 

friichte  in  verschiedenen  Stadien  der  Entwickelung.     Berlin,  1911. 
Seelhorst,   v.:  Versuche   iiber   die   Moglichkeit   einer   Bewurzelung   und 

Adventivtriebbildung  an  oberirdischen  Knoten  von  Getreidepflanzen. 

Jour.  Landw.,  1902. 


CHAPTER  X 
TRITICUM  (Wheat) 

Habit  of  Plant. — Wheat  is  an  annual.  Under  our  cultural 
conditions,  there  are  two  seasonal  forms,  winter  annual,  or 
winter  wheat,  and  summer  annual,  or  spring  wheat. 

Roots. — Wheat  has  a  fibrous  root  system.  ■  In  the  germina- 
tion of  the  grain,  the  primary  root  (Fig.  2)  takes  the  lead; 
very  soon,  two  secondary  roots  appear  on  either  side  of  the 
primary,  thus  forming  a  whorl  of  three.  Later,  other  roots 
may  be  added  to  these.  This  whorl  constitutes  the  primary 
or  temporary  root  system.  It  usually  dies  before  the  plant 
is  fully  grown.  Permanent  roots  appear  in  whorls  at  the 
nodes  some  distance  above  the  three  temporary  roots.  The 
first  whorl  of  permanent  roots  is  generally  about  i  inch  below 
the  soil  surface,  no  matter  at  what  depth  the  grain  was 
planted  (Fig.  3).  In  their  growth,  the  whorls  of  permanent 
roots  curve  outward  and  then  downward,  taking  an  almost 
vertical  course.  They  branch  very  freely  near  the  soil  sur- 
face and  form  within  the  first  foot  a  fine  network,  which 
constitutes  a  large  absorbing  surface.  However,  many  of 
the  roots  of  wheat  reach  a  depth  of  4  feet,  or  even  more  under 
favorable  soil  conditions.  Nobbe  observed  that  the  aggre- 
gate length  of  all  the  roots  of  a  one-year-old  wheat  plant 
amounts  to  500  to  600  meters.  The  number  of  roots  increases 
with  the  number  of  tillers. 

Stems. — The  stems  of  wheat  are  of  the  general  grass  type. 
In  wheat,  there  are  usually  six  joints  (internodes),  the  sixth 
being  the  spike-bearing  one.  The  lowest  joint  usually  re- 
91 


92  BOTANY  OF  CROP  PLANTS 

mains  short,  sometimes  less  than  i  millimeter  long;  the  second 
joint  also  remains  short;  the  sixth  one  is  the  longest. 

Leaf. — The  wheat  leaf  is  of  the  ordinary  grass  type.  The 
blade  varies  considerably;  the  sheath  is  spUt;  the  ligule  is 
thin  and  transparent;  the  auricles  are  conspicuous,  although 
not  as  prominent  as  those  in  barley. 

Inflorescence. — Wheat  flowers  are  arranged  in  spikelets 
and  the  spikelets  into  a  ''head"  or  spike  (Fig.  38).  The 
spike  varies  in  size,  compactness  and  form  in  the  different 
types  of  wheat.  Fifteen  to  twenty  fertile  spikelets  in  a  head 
is  a  fair  average,  but  spikes  have  been  observed  with  a 
number  considerably  greater.  An  abundance  of  water  in 
the  soil  during  the  early  stages  of  development  has  been  found 
to  increase  the  number  of  spikelets  in  a  head.  The  racUs 
or  main  axis  of  the  spikelet  is  zigzag  in  shape  (Fig.  48). 
Each  joint  of  the  rachis  is  flattened  and  curved,  the  concave 
surface  being  on  the  side  next  to  the  spikelet.  There  is  but 
one  spikelet  at  each  joint  of  the  rachis.  There  are  usually 
numerous  short  so-called  "basal  hairs"  at  the  base  of  each 
spikelet.  The  lower  spikelets  of  the  head  are  often  sterile; 
less  frequently,  the  terminal  spikelet  is  sterile  (as  in  einkorn). 

Spikelet. — The  number  of  flowers  in  a  wheat  spikelet 
varies  from  two  to  five.  It  has  been  shown  that  the  number 
of  flowers  that  reach  maturity  in  a  spikelet  may  be  increased 
by  an  ample  supply  of  water  during  the  period  when  the 
flowers  are  developing.  It  is  quite  probable  that  there  is 
a  "critical  period"  in  the  life  of  the  plant  at  which  time  the 
supply  of  moisture  coming  to  the  plant  has  the  maximum 
effect  in  the  production  of  flowers.  This  critical  period  is 
probably  during  the  early  stages  of  flower  formation,  quite 
a  while  before  the  time  of  heading. 

The  wheat  spikelet  dissected  in  Fig.  29  has  four  flowers, 
three  of  which  have  matured  grain.     The  fourth  flower  is 


TRITICUM 


93 


sterile.  In  Fig.  28,  the  lemmas  of  four  flowers  are  visible. 
As  a  rule,  but  two  grains  mature.  In  some  varieties,  most 
of  the  spikelets  mature  three  grains,  and  less  frequently 
four. 

The  glumes  are  broad,  varying  much  in  shape,  color, 
smoothness  or  hairiness,  width  and  distinctness  of  keel, 
length  and  sharpness  of  tip.  It  has  been  shown  that,  in 
general,  the  second  kernel  of  a  spikelet  is  the  heaviest,  the 
first  next  heaviest,  then  the  third,  fourth,  etc. 

Flower  (Fig.  30). — There  are  three  stamens  with  thread- 
like filaments  and  rather  large  anthers.  The  single  ovary 
has  two  feathery  stigmas.  There  are  two  lodicules.  As  was 
pointed  out  on  page  84,  the  palet  represents  the  outer 
perianth  whorl,  and  the  lodicules  the  inner  perianth  whorl. 


A.M. 


Fig.  32. — Opening  of  wheat  flower.      {After  Hays.) 

Opening  of  Flower  and  Pollination. — Hays  has  shown  (in  a 
variety  of  spring  wheat)  that  the  flowers  open  early  in  the 
morning,  the  entire  process  of  pollination  taking  place  within 
about  an  hour  (Fig.  32).  Fruwirth  notes  that,  in  warm 
weather,  blooming  begins  at  4:30  a.m.,  and  continues  at  a 
rapid  rate  until  5:30  a.m.     From  this  latter  hour  until  9:00 


94  BOTANY  OF  CROP  PLANTS 

a.m.,  there  is  less  blooming;  this  is  followed  by  a  period  from 
9:00  a.m.  to  10:00  a.m.  of  more  rapid  blooming,  which  in 
turn  is  followed  by  an  interval  of  less  rapid  rate  up  to  2  -.30 
p.m.;  after  this  there  is  an  increase  in  the  rate  again  until 
3:30  p.m.,  and  from  this  hour  up  to  7:00  p.m.,  only  a  slight 
amount  of  blooming  takes  place.  Fluctuation  in  the  time 
of  blooming  is  less  noticeable  in  einkorn  than  in  other  wheats, 
and  less  marked  on  sultry  days  following  rainy  days  in  all 
types  of  wheat.  Polish  wheat  shows  the  most  marked 
fluctuations.  Temperature  and  moisture  are  certainly  the 
important  external  factors  determining  the  time  of  blooming. 
There  appears  to  be  considerable  variation  even  in  the  same 
variety. 

It  is  stated  that  the  swelling  of  the  lodicules  brings  about 
the  separation  of  the  lemma  and  palet  and  hence  the  open- 
ing of  the  flower.  Grass  flowers  in  which  the  lodicules  are 
membranous  or  wanting  remain  closed,  while  those  in  which 
there  is  only  slight  swelling  of  the  lodicules  open  but  to  a 
small  extent. 

In  the  unopened  wheat  flower,  the  filaments  are  short, 
the  stigmas  erect  and  in  contact.  The  palet  and  lemma 
separate,  first  slowly  and  then  quickly.  The  filaments 
then  elongate  rapidly,  pushing  the  anthers  up  and  outside 
of  the  glumes.  The  anthers  are  shedding  pollen  before  the 
flower  is  fully  open,  and  they  continue  to  do  so  until  it  closes 
again.  All  three  anthers  do  not  always  protrude  from  the 
flower,  and,  in  some  instances,  none  may  escape  before 
the  flower  closes.  The  first  flowers  to  open  are  those  situated 
about  one-third  of  the  way  from  the  tip  of  the  spike.  The 
others  follow  in  succession  above  and  below  this  point. 
Each  flower  remains  open  from  a  half  hour  to  one  hour. 
The  head  completes  its  flowering  usually  in  several  days. 

In  northern  cold  or  wet  climates,  close  pollination   {auto- 


TRITICUM  95 

gamy)  is  the  rule  in  nearly  all  wheats.  Durum  wheat,  how- 
ever, has  the  habit  of  cross-pollination  (xenogamy),  and  it  has 
been  suggested  that  this  behavior  is  partly  responsible  for 
its  better  adaptation  to  dry  climates,  and  for  its  greater  dis- 
ease resistance  and  vigor.  Cross-pollination  is  quite  common 
in  the  primitive  wheat,  which  is  an  inhabitant  of  a  dry,  warm 
country.  It  appears  that  cross-pollination  is  the  rule  in 
hot,  dry  localities,  such  as  certain  parts  of  India. 

Artificial  Cross-pollination. — One  of  the  chief  means  of 
wheat  improvement  is  hybridization.  This  necessitates  the 
operation  of  artificial  cross-pollination.  In  this  process, 
the  glumes  of  the  flower  of  the  female  parent  are  spread 
apart  and  the  three  stamens  removed;  this  is  done  just  before 
the  anthers  are  mature.  On  the  same  day,  or  on  the  follow- 
ing morning,  pollen  is  taken  from  the  mature  anthers  of  the 
plant  to  serve  as  the  male  parent,  and  placed  between  the 
glumes  of  the  flower  from  which  the  stamens  have  been  re- 
moved. The  chances  are  that  the  pollen  will  reach  the 
stigma  branches  of  the  emasculated  flower,  germinate,  and 
effect  cross-fertilization. 

Fertilization  and  Maturing  of  Grain. — Brenchley  states 
that  fertilization  in  wheat  normally  occurs  between  one  and 
two  days  after  pollination.  This  interval  represents  the 
time  necessary  for  the  pollen  grain  to  germinate,  and  for  the 
pollen  tube  to  grow  down  through  the  stigma  to  the  embryo 
sac  in  the  developing  ovule.  This  interval  no  doubt  varies 
in  different  varieties  and  under  different  environmental  con- 
ditions, particularly  temperature.  Cool  weather  will  retard 
germination  of  the  grain,  and  growth  of  the  pollen  tube,  and 
thus  affect  the  "setting"  of  grain. 

After  fertilization,  the  embryo  begins  to  develop,  the  endo- 
sperm to  store  reserve  material,  and  the  seed  and  fruit  walls 
to  undergo  marked  changes. 


96 


BOTANY   OF   CROP   PLANTS 


Embryo. — In  the  very  young  stage,  prior  to  fertilization, 
the  axis  of  the  ovule  is  parallel  with  that  of  the  ovary.  Soon 
in  its  development,  the  ovule  turns  so  that  its  micropyle  is 
directed  downward  (Fig.  2>3)-  At  first,  the  young  ovule 
does  not  fill  the  ovary  cavity,  but  soon  does  so  by  further 
growth.  The  ovule  is  attached  along  its  side  to  the  ovary. 
The  groove  indicates  the  position  and  extent  of  this  at- 
tachment. The  first  pair  of  seminal 
(seed)  rootlets  appears  in  the  embryo 
V  about    four    weeks    after    pollination. 

About  a  week  later,  two  other  rootlets 

(appear  above  the  first  pair,  and 
Brenchley  describes  a  fifth  lateral 
rootlet,  which  does  not  appear  until 
quite  late. 
Endosperm. — In  about  a  week  or  ten 
days  after  fertiUzation,  a  definite  tissue 
is  formed  within  the  embryo  sac.  This 
is  the  endosperm.  About  seven  or 
eight  days  later,  the  aleurone  layer  is 
marked  off,  appearing  first  on  the  dorsal 
side.  According  to  Brenchley,  starch 
first  begins  to  appear  in  the  "flank" 
cells  about  the  eleventh  day  after  pollination.  Eckerson 
points  out  that  the  actual  time  of  the  beginning  of  deposi- 
tion depends  upon  the  relative  activity  of  the  leaves  in 
making  sugar  and  of  the  embryo  in  assimilating  it. 
Infiltration  of  starch  is  complete  in  about  five  weeks 
after  pollination.  It  is  held  that  reserve  nitrogenous 
matter  enters  the  endosperm  at  the  same  time  as  the 
starch. 

Grain  Coats. — Before  fertilization,  the  grain  coats  are  as 
follows : 


ovm 


Fig.  33. — Diagram- 
matic section  of  young 
ovary  of  wheat.  {After 
Bessey.) 


TRITICUM  97 

1.  Outer  epidermis- — one  row  of  cells. 

2.  Parenchyma  layer — many  rows  of  colorless  cells. 

3.  Chlorophyll  layer — one  row  of  cubical  cells,  sometimes 

two,  and  several  in  the  groove  region. 

4.  Inner  epidermis — one  row  of  small  cells. 

5.  Outer  integument — two  layers. 

6.  Inner  integument — two  layers. 

7.  Nucellus — several   layers   of   thin- walled   parenchyma 

cells,  all  bounded  by  a  distinct  nucellar  epidermis. 

The  first  four  regions  listed  above  constitute  the  ovary 
wall  (pericarp).  After  fertilization,  marked  changes  take 
place  in  these  coats.  The  nucellar  tissue,  except  its  epider- 
mis, is  absorbed  by  the  enlarging  embryo.  The  outer  integu- 
ment (5)  and  the  inner  epidermis  (4)  soon  disappear.  At 
first,  starch  is  deposited  in  the  entire  ovary  wall.  At  the 
time  of  resorption  of  the  ovary  wall,  deposition  of  starch 
within  it  ceases,  and  its  appearance  begins  in  the  endosperm. 
Resorption  of  the  ovary  wall  begins  in  the  layer  just  outside 
the  chlorophyll-bearing  layer  and  extends  slowly  out  to  the 
epidermis.  Two  to  four  layers  next  to  the  epidermis  persist 
in  the  mature  grain.  The  chlorophyll  cells  become  longer, 
lose  their  chlorophyll,  and  thicken  their  walls.  In  the  proc- 
ess of  maturation,  the  ovary  wall  or  pericarp  becomes 
firmly  attached  to  the  outer  layer  of  the  inner  integument 
of  the  ovule.  This  behavior  seems  to  be  well  demonstrated 
in  all  grasses  investigated.  The  firm  attachment  of  the  peri- 
carp to  the  ovule  distinguishes  the  grain  or  caryopsis  from 
the  achene. 

Ripening  Stages. — It  is  customary  to  speak  of  four  stages 
in  the  ripening  of  the  grain:  (i)  milk-ripe  or  green-ripe  stage; 
(2)  yellow-ripe,  gold-ripe,  or  "dough"  stage;  (3)  full-ripe 
stage,  and  (4)  dead-ripe  stage. 
7 


98 


BOTANY   OF   CROP  PLANTS 


In  the  milk-ripe  or  green-ripe  stage,  the  embryo  is  already 
fully  developed.  The  grain  changes  from  pale  green  to  dark 
green  in  color,  which  change  Nowacki  explains  as  being  due 
to  the  resorption  of  several  layers  of  the  ovary  wall,  through 
which  the  chlorophyll  layer  now  shows.  The  endosperm  cells 
are  filled  with  a  watery  sap  in  which  are  suspended  a  number 
of  starch  grains;  hence,  when  the  grain  is  squeezed  a  white, 
milky  juice  comes  out. 

In  the  yellow-ripe,  gold-ripe,  or  "dough"  stage,  the  cells 
of  the  ovary  wall  become  thicker.  The  lumina  of  inner  in- 
tegument cells  decrease  in  size,  due  to  an  increase  in  the 
thickness  of  their  walls.  The  color  of  the  grain  changes 
from  green  to  yellow,  and  the  endosperm  becomes  tough  and 
waxy. 

The  full-ripe  stage  follows  close  upon  the  preceding.  As  a 
result  of  water  loss,  the  different  cell  layers  become  dis- 
torted. The  grain  becomes  harder  and  firmer.  Grain  is 
usually  harvested  while  in  this  stage. 

If  the  crop  is  now  left  in  the  field,  the  grain  becomes  brittle; 
itjs  then  said  to  be  in  the  dead-ripe  stage. 

Nowacki  gives  the  following  analyses  of  grains  of  wheat  at 
different  stages  of  development: 


Water  content 
of  grain 


Volume  of  loo 
grains,  cm*. 


Dry  substance 

in  100  grains, 

grams 


Milk-ripe  (o)  July    9 
Milk-ripe  (6)  July  13, 

Yellow-ripe    July  20 

Full-ripe         July  23 


51-47 
47.69 
34-37 
25-73 
12.91 
12.97 


S-31 
5-17 
5-07 
4.28 
3-o8 
3-52 


2.86 
3.58 
4-44 
4.19 
3.80 
4.22 


The  maturity  of  the  grain  appears  to  affect  its  vitality. 
Kedzie  has  shown  that  wheat  collected  in  the  dough  stage 


TRITICUM  99 

yielded  25  bushels  per  acre;  in  the  full-ripe  stage,  30  bushels 
per  acre,  and  in  the  dead-ripe,  28  bushels.  The  dead-ripe 
stage  produced  the  most  vigorous  seed,  as  was  determined  by 
the  length  to  which  the  plumule  would  grow.  For  example, 
in  the  above  experiment  wheat  collected  in  the  dough  stage 
produced  a  plumule  g^inches  long,  in  the  full-ripe  stage  10. i 
inches  long,  and  in  the  dead-ripe  stage  1 1  inches  long.  Similar 
experiments  with  rye  have  shown  that  plants  from  immature 
seeds  lack  vigor,  and  also  that  a  large  percentage  fail  to 
germinate.  There  is  some  experimental  evidence  that  by 
continually  planting  immature  seeds  an  earlier  ripening  strain 
may  be  obtained. 

The  Mature  Grain. — The  average  weight  of  100  kernels  of 
common  bread  wheat  is  about  3.866  grams.  Durum  wheats 
weigh  more  per  100  grains.  Although  the  results  are  con- 
flicting, there  are  insufficient  positive  results  to  warrant  the 
belief  that  large  plump  seeds  will  give  uniformly  greater 
yields  than  small  seeds,  especially  when  such  seeds  are  secured 
by  means  of  the  ordinary  fanning  mill.  It  is  known  that  not 
all  the  grains  in  a  spikelet  are  the  same  size  and  weight — 
the  second  is  the  heaviest,  the  first  and  third  about  equal  in 
weight,  and  the  fourth  and  fifth,  if  present,  are  lightest  of 
all.  It  is  obvious  that  all  grains  from  a  spikelet  regardless 
of  their  size,  have  the  same  heredity.  And  a  light  seed  from 
a  spikelet  usually  will,  under  similar  environmental  condi- 
tions, develop  into  a  plant  with  as  much  vigor  as  one  from  a 
heavy  seed  from  the  same  spikelet.  In  the  selection  of  seed 
wheat,  the  individual  plant  should  be  the  basis  of  selection, 
when  such  method  is  practicable,  rather  than  to  depend 
upon  seed  from  the  bin  or  sack,  which  is  the  offspring  of 
many  different  parent  plants. 

There  is  a  tuft  of  hairs,  the  brush  (Fig.  34)  at  the  small 
(stigmatic)  end  of  the  grain,  and  at  the  opposite  end  the 


BOTANY   OF   CROP   PLANTS 


embryo.  Along  the  side  of  the  grain,  facing  the  palet,  is  a 
groove  or  furrow.  This  groove  marks  the  region  of  attach- 
ment of  seed  to  ovary.  The  position  of  the  embryo  may  be 
seen  easily  at  the  base  of  the  grain.     Fig.  34  shows  a  cross- 


Fig.  34. — Common  wheat  (Triticum  asstivum).  A,  grain,  groove  side;  B, 
grain,  embryo  side;  C,  cross-section  of  grain  through  the  embryo;  D,  cross- 
section  of  grain  beyond  the  embryo. 


. starchu 

'jper 


endosterm 


Fig.  35. — Microscopic  section  of  wheat  grain. 

section  of  a  mature  grain  of  wheat  through  the   embryo 
region.     The  three  primary  roots  are  seen  in  section. 

In  a  cross-section  of  a  mature  wheat  grain,  cut  at  right 
angles  to  its  length,  so  as  not  to  include  the  embryo,  the 
following  layers  may  be  recognized  (Fig.  35) : 


TRITICUM  lOI 

1.  Ovary  wall  or  pericarp,  of  several  cell  layers. 

2.  Testa,  two  layers  of  inner  integument. 

3.  Nucellus. 

4.  Aleur'one  layer,  outermost  layer  of  endosperm. 

5.  Starchy  endosperm. 

Ovary  Wall  or  Pericarp. — The  pericarp  of  the  mature 
grain  is  composed  of  several  layers  of  highly  compressed 
cells,  the  original  cavities  of  which  can  scarcely  be  distin- 
guished. The  walls  are  thickened,  cuticularized  and  lignified. 
The  chlorophyll-bearing  layer,  now  colorless,  is  below  these 
layers.  Its  cells  are  marked  by  numerous^narrow  trans- 
verse pits.  The  outside  wall  of  chlorophyll  cells  is  thin,  while 
the  inside  wall,  next  to  the  integument,  is  thick.  In  tan- 
gential view,  chlorophyll-bearing  cells  appear  strongly 
thickened,  rounded  at  the  ends,  and  closely  fitting,  thus 
leaving  no  intercellular  spaces.  In  rye,  these  same  cells  as 
seen  in  tangential  section  are  pointed  at  the  ends. 

The  grains  of  spelt,  emmer,  and  einkorn  have  the  palet  and 
lemma  attached,  and  in  these  the  pericarp  is  more  weakly 
developed  than  in  the  types  of  wheat  with  naked  grains.  In 
all  wheats,  the  layers  of  the  grain,  both  fruit  and  seed,  are 
much  thinner  at  the  embryo  end  than  in  the  other  parts  of 
the  fruit.  It  is  known  that  the  greatest  amount  of  absorp- 
tion of  water  takes  place  at  the  embryo  end. 

Testa  (episperm). — It  has  been  noted  that,  in  the  develop- 
ing wheat  grain,  the  testa  is  composed  of  two  integuments  of 
two  layers  each.  In  the  ripening  process,  the  outer  integu- 
ment is  entirely  absorbed,  so  that  in  the  mature  grain  the 
testa  consists  of  two  rows  of  cells,  belonging  to  the  inner 
integument.     The  walls  are  slightly  lignified. 

The  coloring  matter  of  the  grain  is  found  in  the  inner  layer 
of  the  testa.     It  is  of  two  kinds,  pale  yellow  and  orange 


I02  BOTANY  OF  CROP  PLANTS 

yellow.  The  proportions  of  these  colors  determine  whether 
the  wheat  is  white,  yellow,  or  red. 

Brown  found  in  Triticum,  as  well  as  in  Avena,  Secale,  and 
Hordeum,  that  the  semi-permeability  of  the  grain  coats  is 
localized  in  the  testa.  It  is  very  probable  that  the  epidermal 
membrane  of  the  nucellus  also  has  semi-permeable  properties, 

Nucellus  (perisperm). — The  epidermis  of  the  nucellus 
surrounds  the  aleurone  layer.  It  is  the  only  remaining 
portion  of  the  nucellar  tissue,  which  was  comparatively  large 
in  the  undeveloped  ovule.  The  mature  nucellus  consists  of 
cells  with  strongly  thickened  walls,  and  with  indistinct 
cavities.  It  is  possible  that  in  some  cases  the  nucellus  is 
completely  absorbed,  and  hence  wanting  in  the  mature 
grain. 

Endosperm. — The  endosperm  consists  of  two  portions, 
starchy  or  floury  endosperm,  and  aleurone  layer.  The  endo- 
sperm constitutes  about  92  per  cent,  of  the  grain's  volume. 
The  cereals  are  cultivated  chiefly  for  the  food  material 
stored  in  the  grain.  In  all  of  them,  the  bulk  of  this  food  is 
found  in  the  endosperm.  The  chief  food  materials  stored  in 
the  endosperm  of  grains  are  starch  and  proteins.  The 
germinating  embryo  makes  use  of  these  foods  in  the  first 
few  days  of  its  growth,  or  until  its  roots  are  taking  substances 
from  the  soil,  and  the  young  leaves  are  manufacturing  food, 
or,  in  other  words,  until  the  young  plant  has  established  its 
independence. 

Aleurone  Layer. — This  is  a  single  layer  of  large  cells  im- 
mediately within  the  nucellus.  The  cells  are  rather  uni- 
formly square  or  rectangular  when  viewed  in  transverse  or 
longitudinal  section,  but  irregular  in  shape  when  viewed  per- 
pendicular to  the  surface.  They  are  stored  largely  with 
aleurone  grains.  This  layer  is  often  erroneously  called  the 
gluten  layer.     The  term  "gluten"  is  only  properly  applied 


TRITICUM 


103 


SO  the  principal  protein  found  in  the  starchy  endosperm,  and 
thould  not  be  used  in  connection  with  the  aleurone  layer. 

Starchy  Endosperm. — This  is  made  up  of  large,  somewhat 
elongated,  thin-walled  cells.  The  longer  axes  of  the  cells 
are  usually  at  right  angles  to  the  grain  surface.  They  are 
filled  for  the  most  part  with  starch  grains.  Protein  granules 
may  be  seen  among  the  starch  grains  by  appropriate  stain- 
ing.    Most,  if  not  all,  of  the  wheat  starch  and  all  of  the 


jfarchy 
akurom- 


jcuiellum- 
coleoptih 

h\ipoco\\jl  — 
em\a5i — - 
'     rooi 


groove 


cylmclric 
ebiflidium 

mscufar 
bundte  of 


growing 
U3t  stem 


coleorhiza^ 


Fig.  36. — Part  of  a  median  lengthwise  section  of  a  grain  of  wheat;  much 
enlarged.     (After  Strasburger.) 


gluten  occur  in  this  part  of  the  endosperm.  The  percentage 
of  gluten  increases  from  the  center  outward;  those  cells 
next  to  the  aleurone  layer  contain  the  largest  amount. 
Embryo. — ^A  median  lengthwise  section  of  the  grain  of 
wheat  shows  well  the  structure  of  the  'embryo  (Fig.  36). 
The  seminal  roots  point  toward  the  micropylar  end.  They 
consist  of  a  primary  rootlet  with  two  pairs  of  laterals. 
According  to  Brenchley,  a  fifth  lateral  rootlet  is  formed  in 
addition  to  the  two  pairs  usually  described.  These  rootlets 
are  surrounded  by  the  root  sheath  or  coleorhiza.    A  very  short 


I04  BOTANY  OF  CROP  PLANTS 

stem,  the  hypocotyl,  is  between  the  primary  root  and  the 
growing  point.  In  other  words,  the  embryonic  stem,  or 
hypocotyl,  terminates  at  the  anterior  end  in  a  growing  point 
and  at  the  posterior  end  it  is  prolonged  into  the  primary  root. 
There  are  several  immature  foliage  leaves  surrounding  the 
growing  point  and  attached  to  the  upper  end  of  the  hypo- 
cotyl. The  growing  point  and  foliage  leaves  are  surrounded 
by  a  leaf  sheath,  the  coleoptile  or  pileole.  At  the  point  where 
the  root  sheath  merges  into  hypocotyledonary  tissue,  there 
is  a  small  projection,  the  epihlast.  Lying  next  to  the  endo- 
sperm is  a  speciahzed  structure,  the  scutellum,  which  is 
attached  to  the  hypocotyl.  It  has  been  suggested  that  the 
scutellum  and  epiblast  represent  two  cotyledons,  one  of 
which  (scutellum)  is  highly  modified,  the  other  (epiblast) 
suppressed. 

We  are  all  familiar  with  the  seedlings  of  bean  or  squash. 
In  these,  there  are  two  cotyledons  (seed  leaves)  which 
are  brought  above  ground  and  function  for  a  while  as 
green  leaves.  Plants  with  two  cotyledons  are  said  to  be 
dicotyledonous.  The  scutellum  of  grasses  is  regarded  as  a 
cotyledon,  morphologically.  Plants  Hke  grasses,  sedges, 
rushes,  liUes,  etc.,  which  have  one  cotyledon  are  said  to  be 
monocotyledonous.  If  the  epiblast  represents  a  rudimentary 
second  cotyledon,  as  its  position  on  the  embryo  would  seem 
to  indicate,  it  stands  as  evidence  of  the  fact  that  monocoty- 
ledonous plants  had  dicotyledonous  ancestry.  Rudimentary 
structures  are  a  great  aid  in  tracing  the  racial  history  of  all 
organisms. 

The  scutellum  remains  in  the  seed  during  germination, 
serving  in  the  absorption  of  and  transfer  of  food  from  the 
endosperm  to  the  growing  regions.  The  outermost  layer 
of  the  scutellum,  where  it  adjoins  the  endosperm,  is  a 
columnar  epithelium.     It  is  probably  this  layer  which  secretes 


TRITICUM  105 

the  enzymes  through  the  action  of  which  the  starches  and 
proteins  in  the  endosperm  are  rendered  soluble  (digested), 
and  which  in  a  soluble  form,  are  enabled  to  pass  from  cell  to 
cell  to  the  tissues  in  the  growing  points. 

The  embryo  is  rich  in  fat  or  oil,  mineral  matter  and  pro- 
tein, and  contains  considerable  quantities  of  soluble  carbo- 
hydrates, but  probably  no  or  very  little  starch.  About  one- 
sixth  of  the  embryo  is  fat  and  one-third  protein,  the  two 
constituting  about  one-half  of  its  weight. 

Bran  Layer. — The  bran  of  wheat  includes  the  three  outer 
layers  of  tissue,  viz.,  pericarp,  testa,  and  nucellus.  The 
pericarp  constitutes  the  larger  proportion  of  the  bran  and 
consists  largely  of  mineral  and  lignified  material.  The  pro- 
tein content  of  the  bran  is  due  to  aleurone  cells  and  starch 
cells  which  adhere  to  bran  layers  in  the  milling  process. 

Commercially  speaking,  bran  consists  of  the  scale-like, 
flaky  outside  covering  which  is  removed  from  the  wheat  in 
the  milling  process.  It  ordinarily  contains,  in  addition  to 
the  pericarp,  testa,  and  nucellus,  all  or  part  of  the  aleurone 
layer  and  some  starchy  endosperm  which  may  adhere  to  it. 

Wheat  bran  varies  considerably  in  chemical  composition, 
and  hence  in  feeding  value,  according  to  the  kind  of  wheat 
used  and  the  milling  process  employed  in  grinding  it.  It 
may  contain  as  low  as  14  per  cent,  and  as  high  as  18  per  cent 
crude  protein,  with  an  average  of  about  16  per  cent. 

Protein  of  Wheat. — According  to  analyses  of  American 
wheats  compiled  in  1890,  the  protein  (nitrogen  X  6.25)  varies 
from  8.1  per  cent,  to  17.2  per  cent.,  with  an  average  of  11. 9 
per  cent.  This  was  in  samples  containing  10.5  per  cent, 
water,  thus  making  the  protein  13.3  per  cent,  of  the  dry 
matter  of  the  grain. 

Osbourne  and  Vorhees  have  recognized  the  following  five 
wheat  proteins:   globulin,   albumin,   proteose,   gliadin,   and 


Io6  BOTANY  OF  CROP  PLANTS 

glutenin.     The  latter  two  proteins  compose  gluten.     Gliadin 
is  the  sticky  substance  in  gluten. 

As  a  general  rule,  grains  that  have  a  marked  glutenous  or 
horny  or  flinty  appearance  are  higher  in  protein  than  those 
that  have  a  starchy  or  dull  appearance.  However,  it  is 
known  that  a  given  variety  may  produce  a  grain  that  is  hard 
and  rich  in  gluten;  or  one  that  is  soft  and  low  in  gluten,  de- 
pending on  the  environmental  factors.  But  it  seems  true, 
nevertheless,  that  the  term  "quality"  refers  to  both  the 
physical  characteristics  and  chemical  composition  of  the 
grain. 

Relative  Proportions  of  the  Parts  of  the  Grain. — 

1.  Bran  (pericarp,  testa,  nucellus),  8  to  9  per  cent. 

2.  Aleurone  layer,  3  to  4  per  cent. 

3.  Starchy  or  floury  endosperm,  82  to  86  per  cent. 

4.  Embryo  or  germ,  about  6  per  cent. 

"Hard"  and  "Soft"  Wheats.— A  "hard"  wheat  is  one  with 
a  horny  or  flinty  texture,  and  quite  high  in  protein.  Hard 
wheats,  as  a  result  of  their  high  gluten  content,  make  a 
"strong"  flour,  which  is  adapted  for  making  Ught  bread. 
A  "soft"  wheat  is  more  easily  crushed  than  a  hard  wheat,  has 
a  starchy  or  dull  appearance,  and  is  relatively  rich  in  starch. 
The  "soft"  wheats  have  been  regarded  with  favor  for  the 
making  of  bread  and  pastry  flours.  However,  the  flour  from 
soft  wheats  is  said  to  be  "weak,"  that  is  incapable  of  making 
a  large  heavy  loaf.  At  first  there  was  much  opposition  to 
hard  wheats,  because  of  difliculties  in  milling  and  baking. 
In  recent  years,  however,  this  opposition  has  been  largely 
overcome. 

There  are  three  classes  of  hard  wheats  in  this  country: 
(i)  hard  spring  wheat,  (2)  hard  winter  wheat,  and  (3) 
durum  wheat.     The  principal  hard  spring  wheats  are  Fife 


TRITICUM  107 

and  Bluestem.  Turkey  and  Kharkov  are  the  chief  hard 
winter  wheats,  and  Kubanka  the  most  important  durum 
wheat.  On  account  of  its  highly  glutenous  character,  durum 
is  used  extensively  in  the  manufacture  of  macaroni  and 
vermicelli.  The  flour  of  this  hard,  glutenous  wheat  is  being 
mixed  with  that  from  the  softer  wheats,  and  the  result  is  a 
flour  of  excellent  bread-making  qualities. 

Much  emphasis  has  been  placed  upon  the  great  influence 
of  climate  upon  the  composition,  hardness  and  quality  of 
wheat.  In  fact,  it  is  claimed,  that  the  soil  has  Httle  or  no 
effect  upon  these  characters.  In  general,  a  hot,  dry  climate 
produces  a  fine-stemmed  plant  the  grain  of  which  is  hard, 
glassy  and  rich  in  nitrogen,  while  a  cool,  moist  climate  pro- 
duces a  coarser-stemmed  plant  the  grain  of  which  is  relatively 
soft,  mealy  and  poor  in  nitrogen.  Headden,  however,  has 
been  able  to  produce  starchy  and  flinty  kernels  at  will  in  the 
same  variety  growing  under  identical  climatic  conditions,  by 
controlling  the  ratio  of  nitrogen  to  potassium.  An  abund- 
ance of  nitrates  produced  a  flinty  grain,  while  a  scarcity  of 
nitrates  in  proportion  to  potash  gave  a  starchy,  mealy 
grain.  This  work  establishes  the  fact  that  the  soil,  as  well 
as  the  climate,  is  a  factor  in  determining  the  quality  of 
wheat. 

Milling  of  Wheat. — The  wheat  is  first  thoroughly  cleaned 
and  scoured  to  remove  sticks,  straw,  fine  dust  particles,  and 
hairs  of  the  brush.  It  is  then  slightly  moistened  with  water, 
in  order  to  prevent  the  pericarp  from  grinding  up  fine.  This 
is  known  as  tempering.  Then  comes  the  process  of  breaking. 
This  consists  in  removing  the  bran  coats  and  embryo  from 
the  endosperm,  and  the  gradual  reduction  of  the  latter  to 
finer  and  finer  particles.  In  this  process  the  grain  is  passed 
between  successive  pairs  of  corrugated  iron  rolls.  The  prod- 
uct of  each  set  of  rolls  is  sifted,  and  the  particles  are  graded 


Io8  BOTANY  OF  CROP  PLANTS 

according  to  size,  the  coarser  particles  passing  on  to  the 
next  set  of  rolls.  Finally,  the  pericarp  layers  are  com- 
pletely separated  from  the  adhering  layers  of  aleurone  and 
starchy  endosperm  cells.  The  finely  ground  parts  of  the  en- 
dosperm are  sifted  and  bolted.  The  material  that  will  pass 
through  fine  silk  bolting  cloth  is  called  flour.  The  larger  and 
coarser  particles  that  remain  behind  are  known  as  middlings. 
The  middlings  are  then  freed  of  particles  of  bran,  i.e.,  purified, 
and  passed  between  several  sets  of  smooth  rolls;  the  product 
of  each  set  of  rolls  is  taken  to  a  machine  which  separates  out 
the  fine  flour.  The  number  of  grades  of  flour,  and  of  other 
products,  will  depend  upon  the  number  of  sets  of  rolls,  and 
the  mesh  of  the  bolts  to  which  the  grain  and  its  ground  prod- 
ucts are  subjected.  Mills  differ  much  in  the  grades  of 
material  turned  out. 

Kinds  of  Flour. — There  are  three  general  sorts  of  flour: 
graham,  entire  wheat,  and  patent  or  straight  bread  flour. 
■"Graham  flour  ^'  is  the  product  obtained  by  grinding  the 
entire  kernel  of  wheat.  Its  name  is  after  that  of  Sylvester 
Graham  (1794-1851),  a  physician  and  writer  on  dietetics. 
"Entire  wheat  flour"  contains  about  one-half  of  the  coarse 
bran.  In  patent  grades  of  flour  all  of  the  bran  is  removed. 
There  are  several  grades  of  patent  flour,  but  the  most  com- 
mon one  on  the  market  is  the  "straight"  or  "standard 
patent."  It  is  usually  a  combination  of  the  so-called  "first 
patent,"  "second  patent,"  and  "first  clear"  flours.  About 
72  to  75  per  cent,  of  the  total  wheat  is  recovered  as  "straight" 
or  "standard  patent"  flour.  It  is  composed  of  floury  endo- 
sperm alone.  The  ordinary  bread  flours  belong  to  this 
grade.  Other  products  of  the  milling  process  are  known  as 
"second  clear"  flour,  used  for  low-grade  bread,  "red  dog" 
also  used  for  low-grade  bread  or  for  cattle  feed,  and  "shorts, " 
"middlings"  and  "bran."     About  25  per  cent,  of  the  grain 


TRITICUM  109 

is  returned  as  shorts,  middlings  and  bran.  The  composition 
of  these  varies  somewhat  with  the  milling  process. 

Germination  of  Wheat. — The  time  required  for  germina- 
tion depends  upon  external  conditions.  The  optimum  tem- 
perature for  the  germination  of  wheat  is  close  to  84°F.,  the 
minimum  40°  to  43°F.,  and  the  maximum  io8°F.  Germina- 
tion will  take  place  under  field  conditions  usually  within 
from  four  to  ten  days.  Nobbe  finds  that  wheat  will 
begin  to  germinate  in  one  and  three-fourth  days  at 
65°F.,  two  days  at  6o°F.,  three  days  at  5o°F.,  and  six  days 
at  4o°F. 

Three  germinating  stages  in  wheat  are  shown  in  Fig.  2. 
The  primary  root  is  the  first  to  appear.  It  ruptures  the 
coleorhiza  which  remains  as  a  collar  about  the  root  where  it 
breaks  through  the  grain  coats.  Very  soon  two  lateral  roots 
appear;  hence  the  primary  root  system  consists  of  a  whorl 
of  three  roots.  The  growing  point  elongates,  the  first  young 
leaf  being  enclosed  by  the  leaf  sheath  or  coleoptile,  a  closed 
and  pointed  organ.  The  coleoptile  protects  the  growing 
point  and  serves  as  a  boring  organ.  The  coleoptile  of  wheat 
has  the  greatest  soil-penetrating  ability  of  the  common 
cereals.  Its  length  varies  with  the  variety  and  with  the 
depth  of  seeding.  The  closed  end  of  the  coleoptile  is 
broken  by  the  first  foliage  leaf.  The  cotyledon  (scutellum) 
is  left  beneath  the  ground. 

Repeated  Germination. — The  grains  of  wheat,  and  the  seeds 
of  a  number  of  other  agricultural  plants,  are  capable  of 
repeated  germination.  A  grain  may  start  to  sprout,  the 
process  be  stopped  by  dryness,  and  sprout  again  if  moisture 
is  available.  Beal  germinated  wheat  and  buckwheat  six 
times,  each  time  allowing  the  root  and  stem  to  grow  to  the 
length  of  the  grain,  with  the  following  results : 


BOTANY   OF   CROP   PLANTS 
Repeated  Germination 


Kind  of  seed 

Per  cent,  germinated 

1st 

2d 

3d 

4th 

Sth 

6th 

Schumacher  wheat 

Clawson  wheat 

Buckwheat 

lOO 
lOO 

loo 

lOO 
lOO 
lOO 

90 

97 
100 

87 
98 
98 

67 
84 
65 

8 
38 
39 

Classification  of  the  Types  of  Wheat. — Hackel  divides  the 
genus  Triticum  into  two  sections,  Aegilops  and  Sitopyros. 
In  the  first,  the  glumes  are  flat  or  rounded  on  the  ba;ck;  in 
the  second,  keeled.  T.  ovata  is  the  principal  species  in  the 
Aegilops  section.  It  occurs  in  southern  Europe,  as  far  east 
as  Turkestan  in  Asia.  The  cultivated  wheats  belong  to  the 
Sitopyros  section. 


Fig.  37. — A,  split  palet  of  einkorn  (Triticum  monococcum)  surrounding  the 
grain;  B,  glume  of  einkorn;  C,  glume  of  club  wheat  (T.  compactum).  •  X  5- 

Key  to  Economic  Types  of  Wheat 

Spikelets  two-flowered,  one  sterile,  one  fertile;  terminal  spikelet  aborted; 
lateral  teeth  of  glumes  acute  (Fig.  37);  palet  dividing  lengthwise  when 
mature.     T.  monococcum  iehakotn). 


TRITICUM  III 

Spikelets  more  than  two-flowered,   two   or   more  fertile;   terminal   spikelct 
developed;  lateral  teeth   of    glumes    obtuse;  palet  remaining  entire  at 
maturity. 
Glumes  as  long  or  usually  longer  than  lemma;    palet  about  two-thirds 

as  long  as  lemma.     T.  polonicum  (Polish  wheat) . 
Glumes  shorter  than  lemma;  palet  nearly  as  long  as  lemma. 

Rachis  brittle,  articulated,  breaking  at  nodes  when  threshed,  the  seg- 
ments remaining  attached  to  spikelets;  spikelets  two-grained  (some- 
times three  in  spelt). 

Spikelets  not  set  thickly  on  stem;  arched  on  inner  side;  adhering  por- 
tion of    rachis  thick,  blunt;    stem  above  with  central  canal.     T. 
spella  (spelt). 
Spikelets  set  thickly  on  stem;  flattened  on  inner  side;  adhering  portion 
of  rachis  slender,  pointed;  stem  above,  with  e.xception  of  narrow 
canal,  fiUed  with  pith.     T.  dicoccum  (emmer). 
Rachis  tenacious,  not  articulated,  remaining  entire  in  threshing;  spikelets 
usually  more  than  two-grained. 

Empty  glumes   sharply  and   broadly  keeled   to  the  base;   lemma 
bearded. 
Spike  with  sides  parallel  or  nearly  so;  glumes  with  a  bloom,  usually 
glabrous;  grain    very    hard,    horny,    long.     T.   durum    (durum 
wheat). 
Spike  short,  crowded,  long-ovate;  glumes  usually  pubescent;  grain 
short,  blunt  and  softer  than  that  of  T.  durum.     T.  lurgidum 
(Poulard  wheat). 
Empty  glumes  keeled  in  upper  half;    rounded    below   (sometimes 
slightly  keeled  in  lower  half);  lemma  sometimes  bearded. 
Spikes  very  short  (rarely  over  2  inches) ;  very  compact  or  crowded; 
thicker  at  apex  than  center  or  base;  grains  small,  short.     T. 
compactum  (club  wheat). 
Spikes  longer  than  2  inches,  open;  sides  usually  parallel  or  nearly 
so.     T.  asllvum-  (common  bread  wheat). 

The  types  of  wheat  fall  into  two  natural  groups,  as  to 
attachment  of  lemma  and  palet  to  grain,  as  follows: 

1.  ''Naked  wheals,''  in  which  the  grain  comes  free  from  the 
lemma  and  palet,  and  the  rachis  is  tenacious  (2\  durum, 
turgidum,  compactum,  cdsiivum,  and  polonicum) . 

2.  ''Spelt  wheats,"  in  which  the  grain  remains  altaclicd 
to  the  lemma  and  palet,  and  the  rachis  is  fragile  {2\  ■moiio- 
coccum,  dicoccum,  and  spelta). 


112  BOTANY  OF  CROP  PLANTS 

Beyerinck  has  succeeded  in  producing  crosses  of  einkorn 
with  dicoccum,  none  of  which  were  fertile,  however.  Aaron- 
sohn  says  that  T.  polonicum  hybridizes  with  the  other  species, 
T.  cEstivum  and  T.  monococcum,  but  the  offspring  are  not 
fertile. 

T.  monococcum  (einkorn)  is  a  small-headed  species  of  no  economic  impor- 
tance in  this  country.     It  is  cultivated  to  some  extent  in  Spain,  Germany, 


Fig.  38. — Spikes  of  the  types  of  wheat,  i,  PoHsh  wheat  (Triticum  polo- 
nicum) ;  2,  club  wheat  (T.  compactum) ;  3,  common  bread  wheat  (T.  asstivum) ; 
4,  Poulard  wheat  (T.  turgidum) ;  5,  durum  wheat  (T.  durum);  6,  spelt  (,T. 
spelta);  7,  emmer  (T.  dicoccum);  8,  einkorn  (T.  monococcum). 


and  Switzerland.  Grains  in  the  ear  have  been  found  in  the  remains  near  the 
homes  of  Swiss  lake-dwellers  of  the  Stone  Age.  It  is  a  native  of  Asia  Minor. 
Triliciim  agilopoidcs  is  considered  to  be  the  wild  form  of  our  cultivated  ein- 
korn. This  wild  species  is  divided  into  the  two  subspecies:  T.  thaondar  and 
T.  boeoticum.  In  the  first,  only  the  lower  flower  is  fertile,  as  a  rule,  but  botli 
bear  awns,  while  in  hoeoHcum  only  the  lower  flower  is  fertile  and  awn-bearing. 
There  is  a  difference  of  opinion  as  to  which  of  these  stem  forms  is  nearest  to 
our  cultivated  einkorn.  T.  cegllopoidcs  differs  from  cultivated  forms  of 
einkorn  in  that  its  spikes  are  more  fragile,  and  the  grains  smaller  and  lighter 
in  color. 


TRITICUM 


"3 


T.  polonicum  (Polish  wheat)  is  not  a  native  of  Poland,  but  occurs  in  Italy 
and  Abyssinia  in  Africa.     It  is  cultivated  to  some  extent  in  this  country. 

T.  spdta  (spelt)  is  the  oldest  grain  cultivated  in  Greece,  Egypt,  and  the 
Roman  Empire.     It  is  of  slight  economic  importance  in  the  United  States. 

T.  dicoccitm  (emmer)  is  of  some  economic  importance  in  this  country, 
especially  in  the  Western  States. 

T.  durum  (durum)  varieties  are  also  known  as  "goose,"  "wild  goose," 
and  "macaroni"  wheats.  They  are  hard  wheats,  particularly  adapted 
Id   the  arid   regions,   where   they  are   better  yielders   than  aslivum  wheats. 


Fig.  39. — Spikelets  of  the  types  of  wheat,  i,  einkorn  (Triticum  monococ- 
cura);  2,  spelt  (T.  spelta) ;  3,  emmer  (T.  dicoccum);  4,  common  bread  wheat 
(T.  xslivum) ;  5,  club  wheat  (T.  compactum) ;  6,  durum  wheat  (T.  durum) ;  7, 
Poulard  wheat  (T.  turgidum) ;  8,  Polish  wheat  (T.  polonicum).  About 
natural  size. 


Durum  wheat  resembles  barley.  Its  heads  are  the  longest  among  the 
wheats.  The  grains  are  hard,  glassy,  often  translucent  and  rather  large. 
T.  lurgidum  (Poulard  wheat)  is  of  little  consequence  in  this  country.  The 
spikes  are  quadrangular  or  rectangular  in  cross-section.  There  is  a  tendency 
to  form  branching  spikes,  as  in  Alaskan  and  Seven-headed  or  Egyptian 
varieties.  Such  varieties  also  go  under  such  common  names  as  Stoner, 
iMiraile,  Eldorado,  Jerusalem,  INIany-headed,  Many-spiked,  Wild  Goose,  etc. 


114  BOTANY    OF    CROP    PLANTS 

T.  compaclum  (club  wheat)  varieties  are  said  to  be  adapted  to  tlie 
Pacific  Coast  and  Rocky  Mountain  States.  In  club  wheats,  the  spikes 
are  only  two  or  three  times  as  long  as  broad,  and  typically  broader 
at  the  top  than  at  the  base,  thus  appearing  somewhat  club-shaped.  'I"lu' 
joints  of  the  rachis  are  very  short,  so  that  the  spikelets  are  crowded  and  often 
stand  outright.      J 

T.  (Bslivum  (common  wheat). — The  bread  wheats  of  the  world  are  large!)- 
varieties  of  ccslivum. 

Origin  of  Wheat. — A  few  years  ago,  Aaronsohn  brought 
from  Syria  a  wild  emmer  which  was  named  by  Koernicke 
Trilicum  dicoccum  dicoccoides  {T.  licrmonis  Cook)  (P'ig. 
40).  Later,  in  an  expedition  in  Upper  Galilee  to  the  north 
of  Lake  Tiberias,  he  found  this  wild  emmer  again,  and,  on 
Mount  Hermon  near  the  village  of  Arny,  he  found  it  very 
common  and  in  a  variety  of  forms.  This  was  at  an  altitude 
of  1,500  to  2,000  meters.  Chodat  concludes  that  wheat  is 
indigenous  to  Syria.  He  considers  that  T.  dicoccum  dicoc- 
coides, a  form  with  a  fragile  rachis,  is  the  primitive  type 
of  wheat.  It  is  interesting  to  note  that  the  grains  of  this 
"wild  wheat"  are  not  inferior  in  weight  or  size  to  those  of 
the  best  cultivated  varieties. 

It  is  well  agreed  that  the  prototype  of  our  cultivated 
wheats,  whatever  it  is,  is  one  with  a  fragile  rachis.  The  rigid 
rachis  is  considered  to  be  developed  by  man.  It  is  known 
that  the  wheats  cultivated  in  most  ancient  times  were  those 
with  fragile  rachises,  such  as  emmer.  Furthermore,  all 
genera  and  species  related  to  wheat,  such  as  Aegilops  and 
Agropyron,  etc.,  have  a  fragile  rachis.  The  only  cultivated 
wheats  of  today  with  brittle  rachises  are  einkorn,  emmer, 
and  spelt. 

It  is  observed  that  cross-pollination  is  more  prevalent  in 
Aaronsohn's  primitive  wheat  than  in  cultivated  forms.  This 
may  be  due  to  the  fact  that  it  grows  in  a  warm,  dry  climate, 
while  most  cultivated  wheats  belong  to  northern  cHmates, 


TRITICUM 


115 


Imc;.    40. — Wild  cimm-r  ni    PalcsUnc  (  InLicuni  dicoccuiii  dicoccoi. 

in  experimental  plat  at  Banl,  California.      (Cook.  LI.  S.  Pep!,  of  Agr.) 


BOTANY    OF    CR01>    PLANTS 


where  cold  or  wet  weather  prevents  Uower  ()i)eniiig.  In 
India,  it  has  been  observed  that  cross-polh'nation  in  wheat  is 
more  frequent  than  in  northern  climates. 

In  the  wild  wheat  of  Palestine,  the  kernels 
are  normally  retained  by  the  spikelet.  It 
differs  also  from  domesticated  wheat  in  the 
order  of  maturity  of  the  spikelets.  In  do- 
mesticated wheat,  the  first  spikelets  to  de- 
velop flowers  are  those  near  the  middle  of 
the  head,  while  in  the  primitive  wheat  the 
terminal  spikelets  are  the  iirst  ones.  Primi- 
tive wheat  also  shows  some  indications  of 
sexual  dimorphism.  Some  plants  have  been 
observed  to  bear  protogynous,  others  pro- 
tandrous,  flowers.  The  spikelets  of  this  wild 
form  never  mature  more  than  two  grains 
(Fig.  41),  and  those  of  the  same  spikelet  are 
unequal  in  size.  The  smaller  grain  is  borne 
by  the  lower  flower  in  the  spikelet;  this 
flower  has  the  longer  awn  too. 

A.  Schulz  thinks  that  many,  but  not  all,  of  the  primi- 
tive wheat  individuals  found  by  Aaronsohn  are  hybrids 
between   T.   agilopoidcs  Ihaoudar  and  dicoccoidcs.     The 
Fig.  41. — Spike-   origin   of    the   different   types  of  cultivated  wheats,  as 
let  of  wild  ernmer  given  by  Schulz,  is  shown  in  the  following: 
(Tnticum      dicoc-  t^-    u  ■  r       i  •  u     -f  •;    ^   -j        •      ^1 

cum  dicoccoides).  '•  ^'''koni  scnes,  of  which  f.  a-gibpoidrs  is  the 
X  21.;.  prototype. 

2.  Emmer  scries,  of  which   T.  dicoccoidcs  is  tlic  stem 
form.     From  this  have  come  dicoccum,  durum,  lurt^iduiii,  and  poloiiicum. 

3.  SpcU  series,  of  which  the  stem  form  is  unknown.     From  this  have  come 
spelld,  compaclum,  wslivuni,  and  capilalum. 


Environmental  Relations. — Wheat  is  grown  under  a  wide 
range  of  temperature  conditions.  Some  varieties  come  to 
maturity  and  yield  well  as  far  as  64°  N.  latitude  in  Norway, 


TRITICUM  117 

and  up  to  8,000  feet  elevation  in  the  Central  Rocky  Moun- 
tains. In  this  last-mentioned  section  wheat  will  yield  a  crop, 
except  in  unusual  years,  where  the  mean  temperature  for  the 
year  is  not  below  38°F.,  and  that  for  the  summer  season  is 
not  below  58°F.  Winter  wheats  are  able  to  resist  low  tem- 
peratures for  longer  periods  than  spring  wheats. 

Plants  differ  widely  in  their  water  economy.  Some  re- 
quire much  more  water  than  others  to  produce  a  unit  of 
dry  matter.  The  water  requirement  of  a  plant  is  defined  as 
the  number  of  units  of  water  absorbed  by  the  plant  in  the 
production  of  a  unit  of  dry  matter.  The  following  data  are 
taken  from  Briggs  and  Shantz: 

WATER-REQmREMENT  DETERMINATIONS   AT  AkRON,   COLORADO,    IQII,   I912, 

AND  1913,  Based  on  the  Production  of  Dry  Matter 

Plant  Mean  of  genus 

Proso 293 

Millet 310 

Sorghum 322 

Corn 368 

Wheat 513 

Barley 534 

Buckwheat 578 

Oats 597 

Rye 685 

Beet,  sugar 397 

Potato 636 

Pea,  Canada  field 788 

Alfalfa 831 

If  the  water  requirement  of  proso  millet  is  regarded  as  i, 
the  water  requirement  for  the  following  crops  is  as  follows: 
millet  1.06;  sorghum  i.io;  corn,  1.26;  wheat  1.76;  barley 
T.83;  oats  2.04;  rye,  2.34;  rice,  2.42. 

The  water  requirement  of  a  plant  is  dependent  upon  a 
number  of  conditions,  chief  of  which  is  the  fertihty  of  the 
soil.     The  water  requirement  is  greater  in  an  unfertile  than 


Il8  BOTANY   or   CROP   PLANTS 

in  a  fertile  soil.  The  application  of  fertilizers  may  increase 
the  total  amount  of  water  taken  in  by  the  plant,  due  to 
increased  plant  growth,  but  the  requirement  per  unit  of 
dry  matter  is  lowered. 

The  effect  of  cUmate  and  soil  on  the  composition  of  the 
grain  has  been  discussed. 

Uses  of  Wheat. — By  far  the  largest  proportion  of  the 
world's  supply  of  flour  is  made  from  wheat.  As  already 
stated,  the  hard  wheats,  particularly  durum  varieties,  are 
used  extensively  in  the  manufacture  of  macaroni  and  alHed 
products.  In  the  manufacture  of  macaroni,  the  wheat  is 
first  ground  into  a  course  product  known  as   "semolina.''^ 


Fig.  42. — Diagram  showing  the  percentage  of  the  world's  wheat  crop  pro- 
duced by  the  different  countries  in  1915. 

It  is  freed  then  of  any  adhering  particles  of  fine  flour  and 
bran.  The  semolina  is  mixed  with  about  30  per  cent,  of 
water,  worked  into  a  stiff  dough,  and  given  a  thorough 
kneeding.  The  dough  is  then  forced  through  a  press,  from 
which  it  issues  in  long  hollow  tubes.  These  tubes  of  moist 
dough  are  then  carefully  dried  in  a  manner  to  prevent  them 
from  becoming  too  brittle  or  sour.     Vermicelli  and  spaghetti 


TRITICUM 


119 


are  also  made  from  semolina  and  water,  but  dies  of  different 
form  are  used,  and  drying  is  done  on  frames.  Many  sorts  of 
breakfast  foods  are  made  from  wheat.  A  very  recent  prod- 
uct is  puffed  wheat,  in  the  preparation  of  which  the  kernels 
are  expanded  by  heating  to  a  high  temperature  under  pres- 
sure, and  then  the  pressure  is  suddenly  released.  The  whole 
grain,  screenings,  bran,  shorts,  middlings  and  "red  dog"  are 
fed  to  animals.  Sometimes  wheat  is  sown  with  vetch  and 
the  two  together  used  for  silage  purposes.  Wheat,  as  well 
as  other  cereals,  finds  use  in  the  manufacture  of  whiskey. 
It  is  employed  also  in  the  making  of  weiss-beer  malt. 

Production  of  Wheat. — The  leading  wheat-producing 
countries  of  the  world  are  shown  graphically  in  Fig.  42. 
The  following  table  gives  the  wheat  production  in  the  United 
States  for  1915. 

Wheat  Production  in  the  United  States,  191 5 


State 

Acres 

Bushels 

Total  value 
dollars 

North  Dakota... .  r. 

8,350,000 
8,525,000 
4,310,000 
3,947,000 
3,725,000 
2,800,000 
2,000,000 
2,750,000 
1,980,000 
21,511,000 

151,970,000 
106,538,000 
73,420,000 
72,154,000 
60,762,000 
53,200,000 
50,394,000 
47,300,000 
40,194,000 
352,573,000 

132,214,000 
94,819,000 
66,678,000 
60,609,000 
54,835,000 
53,200,000 
41,324,000 
48,246,000 
41,802,000 

336,575,000 

Minnesota 

Nebraska 

South  Dakota 

lUinois 

Washington 

Ohio 

All  other  States 

United  States 

59,898,000 

1,011,505,000 

930,302,000 

References 
Aaronsohn,  a.,  and  Schweinfurth,  G.:  Die  AuflSndung  des  wilden  Em- 
mers  (Triticum  dicoccum)  in  Nord  Palastina.     Altneuland  Monatsschr. 
fiir  die  wirtschaftliche  Erschliessung  Palastinas,  Berlin,  Nos.  7-8,  213- 
220,  1906. 


o 
< 

Ul 


iSSlssSss.s.sSSsS 


r^ 


ii.ii 

mm 


iiSi 


III! 


ills 


P-lsllllll 


iiiiiiHii 

illlliS!-!-!- 


ssiisiisSs 


TRITICUM  121 

Aaronsohn,  Aaron:  Agricultural  and  Botanical  Exploration  in  Palestine: 

Wild  Prototypes  of  Wheat  and  Other  Cereals  in  Palestine.     U.  S.  Dept. 

Agr.  Bur.  Plant  Ind.  Bull.  i8o:  36-52,  1910. 
Beijerinck,  M.  W.:  tJber  den  Weizenbastard  Triticum   monococcum  9? 

Triticum    dicoccum  c?.     Nederlandsch  Kruidkundig  Archief.,    ser.    2, 
'  T.  4:  189-201,  1886. 
Bessey,  C.  E.:  The  Structure  of  the  Wheat  Grain.     Nebr,  Agr.  Exp.  Sta. 

Bull.  32:  100-114,  1894. 
Bloomfield,  L.  M.  :  Contributions  to  the  Life  History  of  the  Wheat  Plant 

(T.  vulgare).     Ann.  Rep.  Ohio  State  Acad.  Sci.,  2:  12-14,  1894. 
Brenchley,  W.  E.:  On  the  Strength  and  Development  of  the  Grain  of  Wheat 

(T.  vulgare).     Ann.  Bot.,  23:  11 7-139,  1909. 
Brenchley,  W.  E.,  and  Hall,  A.  D. :  The  Development  of  the  Grain  of 

Wheat.    Jour.  Agr.  Sci.,  3:  195-217,  1909. 
Chodat,  R.:  a  Grain  of  Wheat.     Pop.  Sci.  Mo.,  82:  33-46,  1913. 
Cobb,  N.  A.:  Universal    Nomenclature    of  Wheat.     N.  S.  W.  Dept.  Agr. 

Misc.  Pub.  539,  1905. 
Cook,  O.  F.:  Wild  Wheat  in  Palestine.     U.  S.  Dept.  Agr.  Bur.  Plant  Ind. 

Bull.  274:  1-56,  1913. 
DoNDLiNGER,  P.  T.:  The  Book  of  Wheat.     Orange  Judd  Co.,  1908. 
Eriksson,  J.:  Beitrage  zur  Systematik  des  cultivierten  Weizens.    Landw. 

Versuchsstat.,  45:  37-135.  1894. 
Fruwirth,  C:  Das  Bliihen  von  Weizen  und  Hafer.  Deut.  Landw.  Presse, 

32:  737-739.  747-748,  1905. 
Hays,  Willet  M.,  and  Boss,  Andrew:  Some  Botanical  Characteristics  of 

Wheat.     Minn.  Agr.  Exp.  Sta.  Bull.  62:  391-421,  1899. 
Headden,    W.    P.:   Yellow-berry    in    Wheat.    .Colorado   Agr.    Exp.    Sta. 

Bull.  205;  1-38,  1915. 
KoNDO,  M.:  Studies  on  Heads  of  Wheat  and  Spelt  as  a  Contribution  to 

Exact  Classification.    Landw.  Jahrb.,  45:  713-817,  1913. 
Krause,  Ernst,  H.  S.:  Die  Heimat  des  Spelzes.     Naturw.  Wchenschr.,  25: 

412-414,  1910. 
MoBius,  F. :  Untersuchungen  iiber  die  Sorteneinteilung  bei  Triticum  vul- 
gare.    Inaug.  Diss.,  Giessen,  1913.     Druck  von  F.  StoUberg,  Merseburg. 
Osborne,  T.  B.:  The  Protein  of  Wheat  Kernel.     Carnegie  Inst.  Washington 

Pub.  84:  1-119,  1907. 
ScHULZ,  August:  Abstammung  und  Heimat  des  Weizens.     39  Jahrsber. 

Westfal.  Prov.  Ver.  Wiss.  u.  Kunst  (zu  Munster)  fur  1910-1911,  S. 

147-152,  1911. 

Die  Geschichte  des  Weizens.     Ztschr.  Naturw.,  83:  1-68,  1911. 

Die  Abstammung  des  Weizens.     Mitt.  Naturf.  Gesell.  Halle,  i:  14-17, 

1912. 
Eckerson,  Sophia  H.;  Microchemical  Studies  in  the  Progressive  Develop- 
ment of  the  Wheat  Plant.     Wash.  Agr.  Exp.  Sta.  Bull.  139;  1-20,  1917. 


122  BOTANY   OF   CROP   PLANTS 

Die  Abstammung  des  Einkorns  (T.  monococcum  L.).     Mitt.  Naturf. 

Gesell.  Halle,  2:  12-16,  1913. 

Triticum  aegilopoides  Thaoudar  X  dicoccoides.     Mitt.  Naturf.  Gesell. 

Halle,  2:  17-20,  1913. 
ScoFiELD,  Carl  S.:  The  Algerian  Durum  Wheats:  A  classified  list,  with 

descriptions.     U.  S.  Dept.  Agr.  Bur.  Plant  Ind.  Bull.  7:  1-48,  1902.' 
Ten  Eyck,  A.  M.:  The  Roots  of  Plants.     Kans.  Agr.  Exp.  Sta.  Bull.  127: 

199-252,  1904. 
Thatcher,  R.  W.:  The  Progressive  Development  of  the  Wheat  Kernel. 

Jour.  Amer.  Soc.  Agron.,  5:  203-213,  1913. 
Woods,  Charles,  and  Merrill,  L.  H.:  Entire  Wheat  Flour.     Me.  Agr. 

Exp.  Sta.  Bull.  103:  61-80,  1904. 


CHAPTER  XI 
AVENA  (Oats) 

Habit  of  Plant. — Oats  are  annual.  The  large  majority  of 
varieties  are  summer  annuals;  a  very  few  are  winter  annuals. 

Roots. — The  root  system  of  oats  is  very  similar  to  that  of 
wheat.  The  dense,  fibrous  growth,  which  in  wheat  occurs  in 
about  the  first  foot  of  soil,  is  somewhat  deeper  in  oats. 
The  roots  of  oats  extend  to  a  depth  of  4  or  5  feet.  To  quote 
from  Ten  Eyck,  "Extending  down  from  the  center  of  the 
root  crown  of  each  plant  in  this  example  was  observed  a  short 
rudimentary  root  stem  which  ended  abruptly  with  a  slight 
enlargement  from  which  radiated  a  few  short,  fine,  wire-like 
roots.  Often  the  old  seed  coat  was  found  clinging  to  the 
enlarged  terminus.  The  depth  at  which  the  seed  was 
planted  determined  the  length  of  the  lower  root  stem.  The 
explanation  of  this  rudimentary  growth  is  that  the  seed  was 
planted  too  deep,  or  below  the  point  at  which  soil  conditions 
were  most  favorable  for  starting  the  young  roots;  hence,  the 
root  crown  formed  considerably  above  the  seed,  the  lower  root 
stem  remaining  rudimentary  and  the  little  rootlets  which 
started  from  it  ceasing  to  grow  early  in  the  season." 

Stems. — As  compared  with  wheat,  the  stems  of  oats  are 
larger  in  diameter  and  softer.  The  number  of  joints  in  the 
culm  varies  from  four  to  eight. 

Leaf. — Oats  produce  abundant  leaves.     They  are  broader, 

as  a  rule,  than  those  of  wheat.     The  leaf  sheath  is  closed. 

The  ligule  is  short,  oval,  and  with  distinct  teeth,  thereby 

differing  from  wheat,  rye,  and  barley.     The  young  leaves  are 

123 


124 


BOTANY  OF  CROP  PLANTS 


rolled  to  the  left.     The  auricles  are  lacking,  which  also  dis- 
tinguishes it  from  the  other  cereals. 

Inflorescence. — The  spikelets  of  oats  are  arranged  in  a 
panicle.     The  branching  on  the  main  axis  is  racemose,  that 


Fig.  44. — Diagram  of  oat  inflorescence.     (After  Broili.) 


of  a  higher  order  is  cymose  (Fig.  44).  The  number  of 
whorls  in  a  panicle  ranges  from  four  to  nine,  mostly  five  or 
six.  Apparently,  there  are  a  number  of  primary  branches 
arising  at  a  node.     However,  there  is  only  one  primary  branch, 


AVENA  125 

the  others  being  branches  of  higher  order,  arising  at  the  base 
of  the  primary.     The  branching  decreases  from  bottom  to  top. 
In   banner  oats    {Avena   orientalis),    the   panicle   is  one- 
sided.    In  ordinary  panicle  or  spreading  oats  (Avena  saliva), 


Fig.   45. — A,  contracted,  one-sided  panicle  of  banner  oats  (Avena  orientalis); 
B,  spreading  inflorescence  of  panicle  oats  (Avena  sativa). 


the  branches  spread  toward  all  sides  (Fig.  45).  Four  main 
types  of  panicle  oats  have  been  distinguished  at  the  Svalof 
Experiment  Station,  as  follows:  (i)  Panicle  stiff  and  upright, 
(2)  panicle  pyramidal,  the  branches  long,  slender,  and  rising 


126 


BOTANY  OF  CROP  PLANTS 


weakly,  (3)  panicle  widely  spreading,  (4)  panicle  with 
branches  weak  and  drooping. 

The  number  of  spikelets  in  a  panicle  varies,  an  average 
number  being  near  75.  The  rachis  is  straight  or  only  sHghtly 
undulating.  A  single  spikelet  is  borne  at  the  end  of  a  slender 
pedicel,  which  varies  in  length. 

Spikelet  and  Flower  (Fig.  46).^ — The  number  of  flowers  in 
an  oat  spikelet  varies  from  two  to  live,  rarely  it  is  one. 
Three,  however,  is  the  usual  number.     In  the  so-called  "  single 

^jlerile  3rd  flower 


Fig.   46. — Spikelet  of  panicle  oats  (Avena  sativa).    X  2>2. 

oals,''  but  one  flower,  the  basal,  matures.  In  "twin  oats," 
two  flowers  mature.  Three  kernels  occasionally  mature. 
The  upper  flowers  of  the  spikelet  are  often  staminate  or 
imperfect.  If  a  large  number  of  spikelets  bear  three  kernels, 
there  is  usually  a  reduction  in  the  number  of  spikelets  in  the 
panicle,  as  well  as  in  the  total  weight  of  grain  from  that 
panicle. 

The  two  empty  glumes  are  unequal,  and  longer  than  the 
lemma.  The  lemma  is  rounded  on  the  back,  acute,  and 
usually  bears  an  awn  which  is  dorsally  attached.     As  a  rule, 


AVENA  127 

the  lower  flower  is  the  only  one  to  bear  an  awn.  The  palet 
is  two-toothed,  and  shorter  than  the  lemma.  It  fits  closely 
about  the  grain.  Stamens  three.  Style  branches  two,  plu- 
mose.   Lodicules  two,  very  evident  at  flowering  time. 

Opening  of  Flower  and  Pollination. — The  inflorescence 
opens  at  the  tip  first.  In  oats,  as  in  other  paniculate  types 
of  inflorescences,  there  are  a  number  of  cells  in  the  axils  of 
the  primary  branches  which  become  turgid  and  bring  about 
the  opening  of  the  inflorescence.  The  first  flowers  to  open 
in  the  panicle  are  in  the  middle  spikelets.  The  blooming  of 
the  entire  panicle  is  completed  in  six  to  seven  days.  In  the 
spikelet,  the  lower  flower  opens  first,  then  the  second  and 
third  in  order.  The  chief  blooming  time  of  oats  is  from 
2  :oo  to  4  :oo  p.m.  Blooming  may  continue  at  slackened  speed 
until  7:00  or  8:00  p.m.  A  flower  usually  remains  open  from 
fifty  to  seventy  minutes.  Hence  cross-pollination  is  not 
excluded.  Self-pollination  is  the  rule,  however,  due  to  the 
fact  that  all  three  anthers  seldom  project  from  the  flower. 
In  cool  or  rainy  weather,  flowers  may  not  open  at  all. 

Fertilization,  and  Maturing  of  Grain. — Oats  and  wheat  are 
very  similar  as  to  fertilization.  .  The  oat  grain  passes  through 
the  milk  and  waxy  stages  to  maturity,  as  in  wheat.  After 
the  resorption  of  the  outer  integuments,  resorption  of  the 
parenchyma  layer  begins.  There  is  a  complete  resorption 
of  the  chlorophyll  layer  and  the  inner  epidermis.  There 
seems  to  be  a  less  marked  fusion  of  pericarp  and  seed  coats 
than  in  wheat. 

The  Mature  Grain. — The  kernel  is  firmly  surrounded  by 
the  lemma  and  palet,  except  in  "naked  oats."  The  lemma 
and  palet  form  the  "hull"  (Fig.  47).  The  quaUty  of  oats 
is  judged  largely  on  the  basis  of  per  cent,  hull  and  kernel. 
Hull  usually  forms  from  25  to  33  per  cent,  of  grain  weight, 
but  may  be  as  low  as  20  per  cent,  or  as  high  as  45  per  cent. 


128 


BOTANY  OP  CROP  PLANTS 


The  percentage  of  hull  in  the  upper  grains  of  a  spikelet  is 
less  than  that  of  lower  grains.  It  is  also  stated  that  early- 
ripening  sorts  have  a  greater  percentage  of  hull  than  late- 
ripening  ones.  The  reports  are  conflicting  concerning  the 
percentage  of  hull  in  short  plump  grains  and  in  long  slender 


rachilla 


starchy 
endosperm 


Fig.  47. — A,  mature  grain  of  wild  oats  (A vena  fatua);  B,  mature  grain  of 
cultivated  panicle  oats  (Avena  sativa) ;  C,  grain  of  same  with  "hull "  removed; 
D,  cross-section  of  grain  with  the  "hull."     A,  B  andC,  X5;.D,   Xio. 


ones.  Furthermore,  there  is  no  constant  relation  between 
weight  of  grain  per  bushel  and  per  cent,  of  hull.  However,  if 
an  oat  variety  is  well  adapted  to  a  certain  region,  the  per  cent, 
of  hull  is  quite  generally  lower  than  if  it  is  poorly  adapted. 


AVENA  129 

There  are  marked  differences  in  the  basal  and  upper  grains 
of  a  spikelet.  The  basal  grain  is  the  largest  and  usually 
bears  an  awn;  the  upper  ones  rarely  have  awns.  A  short 
rachilla  (Fig.  47),  which  bears  the  second  grain,  is  at  the 
base  of  the  lower  kernel.  This  rachilla  varies  in  length,  shape 
and  hairiness  in  the  different  oat  varieties.  The  second  grain 
commonly  carries  no  rachilla,  or  only  a  fine,  thread-like  one 
at  the  end  of  which  is  an  immature  grain  or  the  mere  rem- 
nants of  a  third  flower.  The  base  of  the  outer  grain  is  blunt, 
while  that  of  the  inner  is  pointed. 

The  oat  kernel  (Fig.  47)  is  elongated  and  has  a  hairy 
surface.  As  in  wheat,  the  embryo  forms  a  very  small  por- 
tion of  the  kernel.  A  cross-section  of  the  grain  shows  the 
following  coats:  (i)  lemma;  (2)  palet,  of  six  to  eight  cell 
layers;  (3)  pericarp,  a  thin  layer  of  two  or  three  rows  of  cells; 
(4)  testa,  two  layers  of  inner  integument;  (5)  nucellus,  one 
layer;  (6)  aleurone  layer,  two  rows  of  cubical  cells  (some- 
times one) ;  (7)  starchy  endosperm. 

The  starchy  endosperm  of  oats,  unlike  that  of  wheat, 
possesses  no  gluten,  and  hence  it  cannot  be  made  into  light 
bread.  In  this  respect  it  resembles  barley.  The  double  row 
of  aleurone  cells  also  distinguishes  the  oat  grain  from  the 
wheat  grain.  The  other  grain  coats  and  the  embryo  are 
very  similar. 

Germination  of  Oats. — The  cardinal  temperatures  (maxi- 
mum, optimum  and  maximum)  for  oats  are  about  the  same 
as  they  are  for  wheat. 

The  young  shoot  breaks  out  at  the  germ  end,  grows 
underneath  the  lemma,  and  comes  out  at  the  brush  end. 
This  method  of  growth  is  necessitated  by  the  persistence  of 
the  palet  and  lemma.  The  primary  root,  however,  rup- 
tures the  hull.  The  coleoptile  is  closed.  The  first  foliage 
leaf  is  rolled. 
•  9 


130  BOTANY  OF  CROP  PLANTS 

Classification  of  Oats. — The  common  oat  varieties  in  the 
United  States  fall  into  three  species:  Avena  sativa,  A. 
orientalis,  and  A.  nuda.  The  latter  two  are  sometimes 
given  as  varieties  of  A.  sativa. 

Avena  sativa  (panicle  oats). — The  common  oats  belong 
to  this  species.  In  these,  the  panicles  are  spreading  in  all 
directions  (Fig.  45).  A  considerable  number  of  forms  are 
recognized.  Four  main  types,  based  upon  character  of 
panicle,  were  given  on  page  125.  As  to  color  of  grain,  there 
are  white,  yellow,  gray  (winter  oats),  brown  and  black  sorts. 
Some  are  bearded  and  some  are  beardless. 

Avena  orientalis  (banner,  side,  mane,  or  Tatarian  oats) . — 
The  panicles  of  these  species  have  erect  branches  which  are 
close  to  the  main  axis  (Fig.  45).  The]  inflorescence  is  one- 
sided, which  character  has  suggested  the  common  names 
ascribed  to  it.  There  are  beardless-white,  bearded-white, 
beardless-yellow,  beardless-brown,  and  bearded-brown 
varieties. 

Avena  nuda  (naked  or  hull-less  oats). — The  grains  of  this 
oat  fall  from  the  hull  when  threshed.  It  may  be  either  a 
spreading  or  side  type. 

Other  Cultivated  Oats. — In  addition  to  the  three  common 
species  of  oats  given  above,  the  following  species  are  recog- 
nized and  cultivated  in  various  parts  of  the  Old  World: 
Avena  strigosa  (rough  oats),  A.  hrevis  (short  oats),  A.  hyzan- 
tina  (Mediterranean  oats)  and yl.  abyssinica  (Abyssinian  oats). 

Avena  fatua  ("wild  oats")* — The  so-called  "wild  oat"  is 
often  found  in  oat  fields,  and  the  "seed"  may  frequently  occur 
as  an  impurity  in  farm  seed.  The  plant  has  slender  stems, 
which  are  long,  and  hence  it  usually  stands  above  the  culti- 
vated oats.  It  has  three  flowers  to  a  spikelet,  and  the  awns 
on  the  lemmas  are  strongly  bent  (Fig.  47),  thus  differing 
from  common  oats.     Again,  it  is  distinguished  from  the 


AVENA  131 

latter  by  the  long  reddish-brown  hairs  at  the  base  of  the 
lemma  and  on  the  rachilla. 

In  cultivated  sorts,  there  appears  occasionally  the  so-called 
"false  wild  oats,"  differing  in  its  characteristics  both  from 
the  cultivated  varieties  and  the  true  wild  oats.  It  differs 
from  the  cultivated  varieties  in  having  the  long  twisted  and 
bent  awns.  The  kernels,  however,  are  similar  to  those  of  the 
cultivated  varieties. 

Origin  of  Oats. — It  is  held  by  Haussknecht,  Thellung, 
Trabut,  and  others  that  all  the  varieties  belonging  to  A. 
sativa,  A.  orientalis,  and  A.  nuda  have  originated  from  A. 
fatua.  Under  cultivation,  A.  fatua  has  lost  the  fragility  of 
its  articulations,  its  hairs  and,  in  some  instances,  its  awns. 
A.  strigosa  and  A.  brevis  are  derived  from  A.  barbata,  a 
species  growing  wild  in  the  Mediterranean  region,  Persia, 
Mesopotamia,  west  to  Atlantic  Europe  and  Great  Britain. 
A.  ahyssinica  is  originated  from  A.  wiestii,  a  species  in- 
digenous to  North  Africa  and  Arabia.  A.  byzantina  has 
come  from  A.  sterilis,  the  so-called  "animated"  or  "fly" 
oats,  a  wild  form  frequent  in  the  Mediterranean  region. 
Trabut  has  found  in  this  region  all  forms  of  Avena  sterilis 
("sterile"  oats),  beginning  with  those  that  are  small  and 
useless  and  ending  with  the  forms  now  cultivated  there. 
Algerian  oat  {A .  algeriensis)  is  the  common  cultivated  variety 
of  the  sterile  oat. 

All  the  forms  of  oats  derived  from  A .  fatua  are  character- 
ized by  the  easy  separation  of  the  second  flower  from  the 
rachilla,  which  persists  above  the  lower  flower.  In  those 
forms  of  oats  derived  from  A.  sterilis,  on  the  other  hand,  the 
second  flower  does  not  separate  from  the  lower  flower  without 
carrying  away  the  rachilla  at  its  base. 

Environmental  Relations. — Oats  is  adapted  to  a  humid 
moderately  cool  climate,  such  as  is  found  in  the  region  north 


132 


BOTANY  OF   CROP  PLANTS 


of  the  corn  belt  in  the  United  States.  Cool  summers  favor 
the  ripening  of  the  grain;  oats  is  a  better  crop  than  wheat 
at  high  latitudes  and  altitudes.  The  white  and  black  oats 
are  grown  at  higher  latitudes  than  red  and  yellow  sorts;  the 
latter  are  raised  in  the  Southern  States,  some  varieties 
being  sown  as  winter  oats.  Practically  all  of  the  oats  grown 
in  the  Northern  States  is  spring-sown. 

The  water  requirement  of  oats  is  greater  than  that  of 
any  of  the  other  common  cereals.  It  will  thrive  on  soils  too 
wet  for  corn  and  in  general  is  better  adapted  to  heavier  soils. 

Uses  of  Oats. — ^Large  quantities  of  oats  are  consumed 
annually  in  the  form  of  rolled  oats  or  oatmeal.  The  grain 
is  also  a  much  valued  horse  feed,  and  not  infrequently  it  is 
fed  to  poultry.  Oats  are  sometimes  grown  for  pasture,  and 
also  cut  before  reaching  maturity  as  hay.  It  makes  an  ex- 
cellent nurse  crop.  Oat  straw  is  used  as  roughage  for  stock, 
and  as  a  bedding. 

The  Production  of  Oats.^ — As  is  the  case  with  wheat  and 
corn,  the  United  States  also  leads  all  other  countries  in  the 
production  of  oats.  Russia  is  a  close  second.  Iowa, 
Illinois  and  Minnesota  were  the  leading  States  in  191 5. 


Leading  Countries  in  the  Production  of  Oats,  Showing  Acreage  and 
Production,   1915 


Countries 


United  States 

Russia,  European 

Germany 

Canada 

France 

Austria-Hungary 

United  Kingdom 

Sweden 

Argentina 

*  No  ofl&cial  statistics. 


40,780,000 

1,540,362,000 

44,787,000 

1,006,983,000 

c 

650,000,000 
481,035,000 

11,365,000 

9,051,000 

234,924,000 

¥ 

234,924,000 
195,169,000 

4,149,000 

t= 

70,000,000 
62,392,000 

2,869,000 

AVENA  133 

The  Production  of  Oats  in  the  United  States,  1915 


States 

Acres 

Bushels 

Total  value, 
dollars 

Iowa 

4,950,000 
4,343,000 
3,125,000 
2,150,000 
2,450,000 
1,725,000 
2,200,000 
1,683,000 
1,638,000 
1,530,000 
14,986,000 

198,000,000 

195,435,000 

134,375,000 

99,975,000 

98,000,000 

72,450,000 

70,400,000 

69,003,000 

65,520,000 

64,260,000 

472,944,000 

63,360,000 
68,402,000 
43,000,000 
35,991,000 
26,460,000 
20,286,000 
21,824,000 
24,841,000 
22,277,000 
22,490,000 
206,638,000 

Illinois 

North  Dakota 

South  Dakota 

Nebraska 

Ohio 

Indiana 

Michigan. 

All  other  States 

United  States 

40,780,000 

1,540,362,000 

555,569,000 

References 

Atterberg,  a.:  Neues  System  der  Hafervarietaten  nebst  Beschreibung  der 

nordischen  Haferformen.    Landw.     Vers.     Stat.,    39:  171-204,   1881. 
BoHMER,  C:  tJber  die  Systematik  der  Hafersorten  sowie  uber  einige  zuch- 

terisch  wichtige  Eigenschaften  der  Haferispe.     Eerlin,  1909,  P.  Parey. 

Hafer  im  Bilde.     Fiihling's  Landw.  Ztg.,  609-616,  1911. 
Broili,  J.:  Beitrage  zur  Hafer  Morphologic.     Jour.  Landw.,  58:  205-220, 

1910. 

Hafer  im  Bilde.     Arb.   Deut.  Landw.  Gesell.  Heft.,  194,  Berlin,  1911. 

P.  Parey. 
Cannon,  W.  A.:  A  Morphological  Study  of  the  Flower  and  Embryo  of  the 

Wild  Oat,  Avena  fatua  L.     Proc.  Cal.   Acad.    Sci.  Ser.   3,  I,  No.  10: 

329-364,  1900. 
Criddle,  N.  :  The  So-called  White  Wild  Oats  and  What  They  Are.     Ottawa 

Nat.,  23:  127,  1909. 
Wild  Oats  and  False  Wild  Oats;  Their  Nature  and  Distinctive  Charac- 
ters.    Canada  Dept.  Agr.  Bull.  7:  i-ii,  1912. 
Denaiefe  and  Sirodot:  L'avoine,  etc.     Paris,  1902,  210  figures,  pp.  848. 
Fruwith;  C:  Die  Haferrispe  bei  der  Beurteilung  der  Sorten  und  in  der 

Zuchtung.     Fuhling's  Landw.  Ztg.,  S.  289,  1907. 
Haselhope,  E.:  Vergleichende  Untersuchungen  deutscher  und  amerikanis- 

cher  Haferkorner.    Landw.  Vers.  Stat.,  65:  339-349,  1907. 


134  BOTANY   OE   CROP  PLANTS 

Haussknecht,  E.:  Uber  die  Abstammung  des  Saathafers.     Mitt.  Thiiring. 

Bot.  Ver.  N.  F.  Heft,  2:  45-49,  1892. 
Raum,  H.:  Zur  Systematisierung  der  Hafersorten.     Fiihling's  Landw.  Ztg., 

58:  496-501,  1909. 
RrMPAU,  W.:  Die  genetische  Entwicklung  der  verschiedenen  Formen  unserer 

Saatgerste.    Landw.  Jahrb.,  21:  699-702,  1892. 
ScHULz,  A.:  Die  Geschichte  des  Saathafers  I  und  II.     Jahrsber.  Westfal. 

Prov.  Vers.  Wiss.  W.  Kunst.  Munster.,  41:  204-217,  1913. 
Abstammung  und  Heimat  des  Saathafers.     Mitt.  Thuring.  Bot.  Ver.  N. 

F.  Weimar.,  31:  6-1 1,  1914. 
Tannert,  Paul:  Entwickelung  und  Bau  von  BlUte  und  Frucht  von.Avena 

sativaL.  Inaug.  Diss.  Zurich,  1905. 
Thellung,  a.:  Uber  die  Abstammung,  den  systematischen  Wert  und  die 

Kulturgeschichte   der  Saathafer-Arten  (Avena  sativae  Coss.)  Vrtljschr. 

Naturf.  Gesell.     Zurich,  56:293-350,  1911. 
Trabut,  L.  :  Origin  of  Cultivated  Oats.     (Translation)  Jour.  Hered.,  5 :  74-85, 

1915- 
Contribution  a  I'etude  de  I'origine  des  avoines  cultivees.     Compt.  Rend., 

149: 227-229,  1909. 
ViERHAPPER,  F.:  Zur  Systematik  der  Gattung  Avena.  Verhandl.     K.  K. 

Zool.  Bot.  Gesell.  Wein.,  56:  369-370,  1906. 
ZADE:'Die  Zwischenformen  von  Flughafer  (Avena  fatua)  und  Kulturhafer 

(Avena  sativa).     Fiihling's  Landw.  Ztg.,  369-384,  1912. 


CHAPTER  XII 


HORDEUM  (Barley) 

Habit  of  Plant,  Roots,  Stems,  Leaves. — Barley  is  grown  as 
either  a  summer  or  winter  annual.  It  has  been  observed 
that  two-rowed  barley  {H.  distichon),  has  a  distinct  tendency 
toward  the  perennial  habit  like  rye. 
Plants  that  were  mowed  down  in 
July  sent  up  new  sprouts  which  de- 
veloped inflorescences  the  following 
September,  and  after  removing  these, 
a  third  set  of  sprouts  was  sent  up. 
It  has  been  suggested  that  our  culti- 
vated barleys  are  derived  from  a 
perennial  form  and  that  in  the  course 
of  time  this  habit  has  been  lost. 

The  root  system  of  barley  resem- 
bles that  of  oats.  The  culm  has 
from  five  to  seven  joints,  sometimes 
eight,  the  length  of  which  increases 
from  below  upward.  Barley  does 
not  tiller  as  abundantly  as  oats  and 
winter  wheat.  The  leaves  resemble 
those  of  wheat.  The  auricles,  how- 
ever, are  usually  very  much  pro- 
nounced, and  may  be  used  as  a  basis  of  distinction  between 
the  straws  (Fig.  26). 

Inflorescence. — The  inflorescence  is  a  cyUndrical  spike, 
the  shape  of  which  varies  slightly  in  the  different  barley 
13  s 


Fig.  48. — Rachises  of 
three  common  cereals. 
A,  barley;  B,  wheat;  C, 
rye.      X  5- 


136 


BOTANY   OF   CROP   PLANTS 


types.  The  rachis  is  strongly  compressed.  Opposite  each 
point  on  the  rachis  where  the  spikelets  stand,  there  is  a 
sharply  defined  horizontal  cushion  (Fig.  48).  This  dis- 
tinguishes the  barley  rachis  from  that  of  wheat  and  rye. 
Furthermore,  the  single  joints  of  the  barley  rachis  are 
straight,  while  in  wheat  and  rye  they  are  bent. 


Fig.  49. — ^.-triplet  of  spikelets  of  six-rowed  barley  (Hordeum  vulgare 
hexastichon) ;  note  that  there  are  three  fertile  spikelets  at  the  rachis  joint; 
B,  triplet  of  spikelets  of  two-rowed  barley  (H.  distichon);  the  two  lateral 
spikelets  are  sterile;  C,  single  spikelet  of  hooded  barley  (H.  vulgare  tri- 
f  urcatum) . 

At  each  joint  of  the  rachis,  there  are  three  spikelets,  each 
one-flowered  (Figs.  49  and  50).  The  lateral  spikelets  of  each 
triplet  are  sometimes  imperfect,  as  in  two-rowed  barley. 
Each  spikelet  is  on  a  short  branch  or  rachilla,  which  is  pro- 
duced beyond  the  flower  and  appears  as  a  bristle  (Fig.  51) 
lying  within  the  groove  of  the  grain.     As  in  wheat,  there  is 


iiORDF.ri\r  137 


no  ;i|)iciil  si)ikclcL  in   barley.     The  groups  of  spikelets  are 
arranged  alternately  on  the  rachis. 

Spikelet  and  Flower. — Each  spikelet  is  one-flowered.     The 
glumes  are  narrow  and  awn-like,  forming  an  apparent  in- 


FiG.  50. —  I,  triplet  of  spikelets  of  six-rowed  barley  (Hordeum  vulgare 
liL-xastichon);  2,  of  hooded  barley  (H.  vulgare  trifurcatum);  3,  of  medium 
barley  (H.  vulgare  intermedium);  4,  of  two-rowed  barley  (H.  distichon).  Nat. 
size. 


volucre  about  the  spikelets.  The  lemma  is  broad,  rounded 
on  the  back,  five-nerved  at  the  apex  and  bears  a  long  awn 
with  strongly  barbed  edges.  In  threshing  barley  care  is 
taken  not  to  break  the  awn  so  close  that  the  end  of  the  kernel 


138 


BOTANY    OF   CROP    PLANTS 


is  exposed,  for  by  so  doing,  a  point  of  attack  for  molds  is 

furnished. 

The  palet  is  about  the  same  length  as  the  lemma,  and  bears 

two  ridges.     The  styles  are  short,  and  the  two  lodicules  are 

conspicuous  and  vary  in  the 
different  types. 

Opening  of  Flower  and 
Pollination. — The  blooming 
of  a  spike  begins  slightly 
above  the  middle  and  pro- 
ceeds from  this  point  upward 
and  downward.  The  middle 
flowers  of  a  triplet  come  to 
maturity  earlier  than  the 
laterals.  The  duration  of 
blooming  varies.  Three  to 
four  days  is  a  good  average 
for  a  single  spike,  and  seven 
to  nine  days  for  all  spikes  of 
a  plant.  The  glumes  of  a 
flower  remain  open  from 
twenty  to  thirty  minutes. 
This  period  depends  upon 
weather  conditions. 

In  two-rowed  nodding 
barley,  the  lateral  flowers 
bloom  with  open  glumes, 
while  the  middle  ones  seldom 
open.       Four-rowed    barley 

almost  always  blooms  with  open  flowers,  both  middle  and 

side.       In   two-rowed   erect   barley,    six-rowed   barley   and 

peacock    barley,    the    flowers    bloom    with    closed    glumes. 

It   is   claimed   that,    in    such    cases,   the   lodicules   are   too 


-  lemma 

itarchv 
endojpermi 


Fig.  51. — A,  barley  grain  with  th 
"hull;"  B,  with  "hull"  removed;  C 
grain  in  cross-section. 


HORDEUM  139 

weak  to  force  the  glumes  apart.  In  four-rowed  barley, 
in  which  open  flowers  are  the  rule,  lodicules  are  well 
developed.  It  would  seem,  then,  that  in  four-rowed 
barley  and  two-rowed  nodding  barley,  there  is  a  possi- 
bility of  cross-polHnation,  while  in  six-rowed,  peacock, 
and  two-rowed  erect  barleys  this  possibility  is  excluded. 
However,  very  few  positive  cases  of  natural  hybridization 
of  barleys  have  been  observed.  The  reason  for  this  prob- 
ably is  that  the  styles  are  short  and  do  not  protrude  beyond 
the  glumes.  Rimpau  examined  a  large  number  of  sorts,  and 
in  all,  found  but  eight  sure  cases  of  crossing,  and  these  were  in 
four-rowed  barleys.  Self-pollination  is  the  rule,  which  means 
that  under  field  conditions  there  is  little  danger  that  a  pure 
strain  will  become  impure  through  the  introduction  of 
characters  brought  in  by  the  pollen  grains  of  undesirable 
strains. 

Blooming  in  barley  begins  between  5:30  and  6:00  a.m., 
increasing  in  intensity  up  to  8:00  a.m.  Very  little  blooming 
occurs  in  the  middle  of  the  day.  There  is  a^  slight  amount 
between  3  and  5  o'clock  in  the  afternoon,  but  by  8  in  the 
evening  all  blooming  has  ceased. 

As  in  all  cereals,  blooming  is  dependent  upon  the  weather. 
Barleys  that  normally  bloom  with  open  glumes  on  a  day  with 
high  temperature  and  dry  atmosphere,  may  bloom  with 
closed  or  only  slightly  open  glumes  on  a  cool,  moist  day. 

Fertilization  and  Maturing  of  Grain. — The  immature  grain 
has  much  the  same  structure  as  that  of  wheat.  Kudelka 
finds  that,  in  barley,  the  chlorophyll-bearing  layer  consists 
of  two  rows  of  cells,  however.  As  in  wheat,  there  is  an 
early  resorption  of  the  two  layers  of  the  outer  integument, 
and  of  pericarp  and  nucellar  cells.  The  barley  grain  passes 
through  the  milk-ripe,  yellow-ripe,  full-ripe,  and  dead-ripe 
stages. 


I40  BOTANY  OF  CROP  PLANTS 

Mature  Grain  of  Barley. — In  hulled  barleys,  the  palet  and 
lemma  are  firmly  attached  to  the  kernel  (Fig.  51).  In  the 
so-called  "naked"  or  hull-less  barley,  these  scales  come  loose 
from  the  kernel,  as  in  common  wheat.  The  kernel  of  naked 
barley  resembles  that  of  wheat.  It  is,  however,  pointed  at 
both  ends  (Fig.  51).  The  kernels  are  broadest  at  the 
middle,  in  two-rowed  barleys,  while  in  the  four-rowed  types 
the  kernels  from  the  outer  rows  of  the  head  are  slightly 
twisted  and  those  from  the  middle  rows  are  broadest  near 
the  tip. 

In  the  hulled  barleys,  a  rachilla  ("basal  bristle")  persists 
at  the  base  of  the  grain  on  the  side  adjacent  to  the  palet 
(Fig.  51).  The  character  of  this  bristle  is  of  some  syste- 
matic importance. 

The  hull  may  form  from  10  to  25  per  cent,  of  the  grain, 
being  greater  in  six-rowed  types  than  in  two-rowed  types. 
Variation  in  percentage  of  glumes  may  depend  upon  season, 
soil,  grain  shape,  and  perhaps  fertilizers.  Furthermore, 
Haberlandt  has  shown  that  barleys  of  northern  regions  have 
a  smaller  percentage  of  hull  than  those  of  southern  localities. 

In  a  cross-section  of  the  mature  grain  of  hulled  barley,  the 
following  coats  are  seen: 

1.  Lemma  and  palet,  five  to  seven  rows  of  cells. 

2.  Pericarp,  consisting  of  several  rows  of  parenchyma  cells 
and  two  rows  of  chlorophyll-bearing  cells. 

3.  Testa,  two  layers  of  inner  integument. 

4.  Nucellus,  one  row  of  cells. 

5.  Aleurone  layer,  usually  of  three  (two  to  four)  rows  of 
thick-walled  cells. 

6.  Starchy  endosperm. 

As  in  rye  and  wheat,  the  fruit  and  seed  coats  are  more 
weakly  developed  at  the  embryo  end  than  in  other  parts  of 
the  igrain. 


HORDEUM  141 

The  embryo  of  barley  is  very  similar  to  that  of  wheat. 
It  occupies  but  a  small  part  of  the  grain.  Five  to  eight 
secondary  rootlets  occur.  The  epiblast  is  absent  in  the  genus 
Hordeum.  The  endosperm  varies  from  mealy  to  glassy  or 
translucent.  Mealiness  is  the  result  of  a  high  percentage  of 
starch,  while  translucency  indicates  a  high  percentage  of 
protein.  The  relative  amounts  of  starch  and  protein  in  the 
different  types  vary.  The  two-rowed  barleys  are  used  almost 
exclusively  in  brewing. 

There  is  no  gluten  in  barley  grains,  and  for  this  reason 
light  bread  cannot  be  made  from  the  flour. 

Color  of  Grain. — Harlan  has  made  a  study  of  the  color  of 
barley  grains.  He  says:  "There  are  two  coloring  materials 
in  barley:  One,  anthocyanin,  is  red  in  its  acid  and  blue  in 
its  alkaHne  condition;  the  other,  a  melanin-Hke  compound, 
is  black.  The  pigments  may  occur  in  the  hulls,  the  peri- 
carp, the  aleurone  layer,  and  occasionally  in  the  starch  endo- 
sperm. The  resulting  colors  of  the  grain  are  quite  compli- 
cated. White  denotes  the  absence  of  all  pigment;  a  heavy 
deposit  of  the  melanin-like  compound  in  the  hulls  results  in 
black;  a  light  deposit,  brown.  Anthocyanin  in  the  hulls  re- 
sults in  a  Ught  violet-red.  In  naked  forms  the  melanin- 
like compound  in  the  pericarp  results  in  a  black  kernel; 
anthocyanin  produces  a  violet  one.  The  acid  condition  of 
anthocyanin  in  the  pericarp  superimposed  upon  the  alkaline 
condition  in  the  aleurone  layer  gives  the  effect  of  a  purple 
color,  while  a  blue  aleurone  beneath  a  colorless  pericarp  is 
blue-gray.  White  hulls  over  a  blue  aleurone  cause  the  grain 
to  appear  bluish  or  bluish  gray.  Black  hulls  over  a  blue 
aleurone  give,  of  course,  a  black  appearance.  The  antho- 
cyanin is  always  violet  in  the  hulls  and  in  the  pericarp,  show- 
ing that  these  tissues  are  in  an  acid  condition,  and  always  blue 
in  the  aleurone  layer,  showing  an  alkaline  condition.     The 


142  BOTANY  OF  CROP  PLANTS 

occurrence  of  anthocyanin  in  the  pericarp  of  hull-less  barleys 
is  more  significant  than  its  production  in  the  aleurone  layer." 

Germination  of  Barley. — Haberlandt  gives  the  following 
as  the  germinating  temperatures  of  barley:  optimum  68°F., 
minimum  37.4°  to  39.2°F.,  maximum  82.4°  to  86°F.  In 
brewing,  much  emphasis  is  placed  upon  the  "germinating 
energy"  of  the  grain.  By  this  is  meant  its  ability  to  germi- 
nate within  a  specified  time.  A  high  germinating  energy  is 
96  per  cent,  in  seventy-two  hours  when  kept  at  64.4°  to 
68°F. 

Much  importance  is  attached  to  the  secretion  of  enzymes 
and  the  conversion  of  endosperm  in  the  germinating  of  barley 
grain.  A  barley  of  high  diastatic  power  is  preferred;  by  this 
is  meant  the  ability  to  produce  an  abundance  of  the  starch- 
dissolving  enzyme— diastase.  Small  grains,  with  a  high 
nitrogen  content  have  a  high  power  of  forming  the  enzy- 
matic secretions.  The  enzymes  secreted  during  germination 
are  chiefly  diastase,  cytase,  and  proteases,  and  it  is  quite 
probable  that  the  epithelial  layer  of  the  scutellum  is  the 
secreting  organ.  It  has  been  pointed  out  by  Mann  and 
Harlan  that  "the  greatest  secreting  area  for  a  given  grain 
is  secured  with  a  scutellum  extending  well  over  the  edges  of 
the  adjacent  endosperm;  the  greatest  vigor  in  an  epithelial 
layer  of  long,  narrow  cells,  the  highest  condition  of  efl&ciency 
in  a  well-matured,  well-cured  grain."  As  has  been  indicated, 
the  principal  enzyme  secreted  by  the  germinating  embryo 
is  diastase.  It  has  the  specific  property  of  changing  starch 
to  sugar.  Hence,  the  reserve  starch  in  the  embryo,  converted 
to  soluble  and  diffusible  sugar,  serves  to  nourish  the  young 
plant.  Cytase  is  a  cellulose-dissolving  enzyme.  Protease 
renders  the  insoluble  proteins  soluble. 

The  primary  root  is  the  first  to  appear.  This  is  followed 
by  the  secondary  ones,  and  the  young  shoot.     The  shoot 


HORDEUM 


143 


grows  under  the  lemma  and  palet  to  the  anterior  end  of  the 
grain  and  there  becomes  free.     The  coleoptile  then  opens 


Jemma 
/  yindicule 
jtamen 


Fig.  52.— Diagrams  showing  the  relative  position  of  spikelets  in  barleys 
A.  six-rowed  (Hordeum  vulgare  hexastichon) ;  B,  four-rowed  barley  (H  vul- 
gare  pallidum);  C.  two-rowed  barley  (H.  distichon);  D.  medium  barley  (H 
vulgare  intermedium).     (After  Broili.) 

and  the  first  foliage  leaf  appears.     In  the  germination  of 
barley,  the  young  leaves  become  twisted.     This  is  character- 


144  BOTANY  OF  CROP  PLANTS 

istic  of  barley.  The  term  ^^  aero  spire''  is  sometimes  applied 
to  these  leaves. 

The  crown  roots  are  formed  at  a  rather  constant  soil  level. 
If  the  grain  is  planted  deep,  a  long  internode  is  formed,  such 
that  adventitious  roots  are  produced  at  the  proper  level. 

Classification  of  Barleys. — There  is  much  difference  of 
opinion  concerning  the  classification  of  the  cultivated  barleys. 
There  are  at  least  two  distinct  species:  Hordeum  vulgare,  in- 
cluding the  six-rowed  barleys,  and  Hordeum  distichon, 
including  the  two-rowed  barleys. 

Hordeum  vulgare  hexastichon  (six-rowed  barley). — It  will 
be  recalled  that,  in  the  barleys,  there  are  three  one-flowered 
spikelets  at  each  joint  of  the  rachis.  In  the  six-rowed  type, 
every  flower  of  a  triplet  is  fertile.  The  spikelets  are  in  six 
distinct  rows  and  stand  out  equidistant  from  the  rachis. 
Furthermore,  the  rows  are  equal  distances  from  each  other 
about  the  axis.  These  points  are  shown  in  Fig.  52.  The 
lemmas  of  all  three  spikelets  are  bearded.  The  rachis  inter- 
nodes  are  very  short,  from  2.1  to  2.7  millimeters  long.  The 
kernels  from  the  outer  rows  are  twisted,  those  from  the 
middle  row  broadest  near  the  tip,  and  symmetrical.  The 
"hull"  is  thick.  These  are  both  winter  and  spring  sorts. 
Six-rowed  types  are  food  barleys. 

Hordeum  vulgare  (common  six-rowed  barley). — This  is 
sometimes  called  a  four-rowed  barley.  Every  spikelet  is 
fertile;  the  lemmas  of  all  spikelets  are  bearded  or  hooded; 
the  "hull"  is  thick;  and  there  is  a  high  percentage  of  protein. 
It  differs  from  six-rowed  barley  in  that  the  rows  of  grains  are 
not  equal  distances  from  each  other  about  the  axis  (Fig. 
52).  The  lateral  grains  of  one  triplet  tend  to  overlap  with 
the  lateral  grains  of  the  triplet  on  the  opposite  side  of  the 
rachis.  Hence,  there  will  be  found  often  four  rows  of  grains, 
the  central  grains  of  each  triplet  forming  two  rows  and  the 


IIORDEUM  145 

overlapping  laterals  also  forming  two  rows.  Furthermore, 
in  four-rowed  barley,  the  rachis  internodes  are  longer  (2.8 
to  3.5  millimeters)  than  those  in  six-rowed  barley,  and  this 
results  in  a  more  loosely  arranged  spike. 

A  form  of  four-rowed  barley,  Hordetim  vidgare  pallidum, 
is  the  common  barley  in  northern  Europe,  Asia,  and  America. 
There  are  both  winter  and  summer  forms.  Hordeum  vulgare 
trifurcatum  is  the  four-rowed  Nepal  barley.  In  this,  the 
lemmas  each  have  three  pronged  awns  which  bend  back  in 
the  form  of  small  horns  or  hoods  (Fig.  49).  It  is  also  often 
called  "hooded  barley."  There  are  both  naked  and  hulled 
hooded  barleys.  Hordeum  vulgare  coerulescens  is  blue  barley, 
//.  vulgare  nigrum,  black  barley,  and  H.  vulgare  coelesle,  the 
hull-less  Jerusalem  barley. 

Hordeum  vidgare  intermedium  (medium  or  hybrid  barley). — 
Under  this  name  are  included  those  barleys  that  are  transition 
forms  between  the  two-  and  many-rowed  types  (Fig.  52).  In 
these  intermediate  forms,  only  the  two  middle  rows  are  nor- 
mally formed,  the  four  lateral  ones  being  beardless  and  smaller. 
It  is  quite  probable  that  the  ////(T/^/c^/mw  forms  are  segregates 
of  the  hybrids  of  certain  two-rowed  and  many-rowed  forms. 

Hordeum  disliclion  (two-rowed  barley). — In  this,  the 
spikes  bear  two  longitudinal  rows  of  grains.  As  in  six-rowed 
barley,  the  spikelets  occur  in  groups  of  three  on  opposite 
sides  of  the  rachis,  but  in  the  case  of  two-rowed  barley,  the 
lateral  spikelets  of  each  triplet  do  not  mature,  only  the  middle 
one  of  each  maturing  its  grain  (Figs.  49  and  52).  However, 
the  glumes  of  the  lateral  spikelets  develop  normally.  'I'he 
anthers  of  side  spikelets  may  be  either  dwarfed  or  well 
developed.  The  kernels  of  two-rowed  barleys  are  symmet- 
rical and  broadest  in  the  middle.  The  hull  is  thin.  There  is 
a  low  percentage  of  protein  and  a  mealy  endosperm. 

There  are  four  rather  common  types  of  two-rowed  barleys: 


146 


BOTANY   OF    CROP    PLANTS 


I.  Uordeum  dislichon   zeocriton  (peacock   or    fan   barley) 
(Fig.  53). — The  spikes  are  very   dense   and   short,  about  6 


Fig.  53. — Spikes  of  barleys,  i,  two-rowed  nodding  barley  (Hordeuni  dis- 
tichon  nutans);  2,  medium  barley  (H.  vulgare  intermedium);  3,  four-rowed 
barley  (H.  vulgare  pallidum);  4,  hooded  barley  (H.  vvdgare  trifurcatum);  5, 
six.-rowed  barley  (H.  vulgare  hexaslichon). 


centimeters  long,  broad  at  the  base  and  narrow  at  the  tip, 
and  with  widely  spreading  beards. 

2.  Uordeum  dislicJion   nudum  (two-rowed    naked   barley). 


HORDEUM 


147 


3.  Hordeum  distichon  erectum  (erect-eared  barley). — In 
this  the  heads  are  erect  and  broad.  On  the  dorsal  side  of 
the  grain  at  the  base,  there  is  a  characteristic  crown  furrow, 
so  that  in  longitudinal  section  a  rounded  hump  shows  (Fig. 
54).  Rachis  joints  are  from  2.1  to  2.7  millimeters  long. 
The  rachilla  is  hairy  and  broadened. 


Fig.  54. — Bases  of  the  grains  of  two-rowed  barleys.  A,  5,  nodding  barley 
(Hordeum  distichon  nutans);  C,  D,  erect-eared  barley  (H.  distichon  erec- 
tum).    (After  Newman.) 


4.  Hordeum  distichon  nutans  (bent  or  nodding  barley). — 
In  this  the  heads  hang  down  when  ripe.  On  the  dorsal  side 
of  the  grain  at  the  base,  there  is  a  slight  horseshoe-shaped 
depression.  In  lengthwise  section,  the  base  of  the  kernel 
slopes  off  (Fig.  54).     Rachis  joints  are  2 .8  to  3.5  millimeters 


148  BOTANY    OF    CROP    PL.A^^TS 

long.  The  rachilla  is  broom-form  or  very  hairy.  The  noted 
malt  barley.  Chevalier,  belongs  to  this  t>'pe. 

Origin  of  Cultivated  Barleys. — There  are  two  principal 
opinions  regarding  the  origin  of  cultivated  barley,  that  of 
Koernicke  and  that  of  Rimpau.  Koernicke  considers  Hor- 
deum  spontaneum  to  be  the  prototype  of  all  our  cultural 
forms.  This  wild  barley  is  nearest  related  to  the  nutans 
form  of  two-rowed  barley,  being  distinguished  from  the 
latter  by  its  more  fragile  rachis,  less  compressed  spike, 
stronger  awns,  larger  side  spikelets,  perennial  habit,  and  its 
stronger  tendency  to  tiller.  The  variety  nutans  first  arose 
from  the  wild  form.  From  this  came  erectum,  by  a  shorten- 
ing of  the  rachis  joints.  From  erectum,  came  zeocriton  by 
still  greater  shortening  of  rachis  joints,  and  an  enlargement 
of  the  fruit  toward  the  base.  From  nutans  also,  there  arose 
the  four-rowed  barley,  by  the  side  spikelets  becoming 
fertile.  From  erectum  and  zeocriton,  there  came  sLx-rowed 
barleys. 

Rimpau,  on  the  other  hand,  considers  the  six-rowed 
bearded  barley  as  the  prototv-pe  of  all  other  barley  tjpes. 
Through  a  process  in  which  side  spikelets  become  rudimen- 
tary, there  arose  the  various  four-  and  two-rowed  tx-pes. 
Rimpau  bases  his  opinion  on  the  nature  of  the  offspring 
between  zeocriton  and  trifurcatum. 

Environmental  Relations. — Winter  barleys  are  less  resist- 
ant to  winter  cold  than  either  "w-inter  wheat  or  winter  rye. 
Consequently,  in  the  Northern  States  practically  all  barley 
is  spring-sown.  As  a  spring-sown  crop  it  has  a  wide  geo- 
graphical range.  It  is  grown  as  far  as  65°  X.  latitude  in 
Alaska,  and  to  an  altitude  of  7,500  feet  in  the  Rocky  Moun- 
tains. At  higher  elevations  it  is  grown  as  a  hay,  the  chief 
variety  being  "bald  barlev. "  Bqiey  also  does  well  in 
southern  Cahfornia. 


HORDEUM  149 

Barley  stands  between  oats  and  wheat  in  its  water 
requirement. 

Uses  of  Barley. — Barley  has  a  great  variety  of  uses.  Its 
greatest  use  is  in  the  preparation  of  malt.  The  two-rowed 
barleys  have  larger  and  softer  grains  than  six-rowed  barleys 
and  therefore  are  preferred  for  malting  purposes.  Smaller 
quantities  are  ground  into  flour  from  which  bread  is  made. 
"Pearl  barley"  (grains  with  the  lemma  and  palet  removed)  is 
used  for  soups.  Barley  enters  into  a  few  cereal  breakfast 
foods.  It  is  a  valuable  stock  feed,  especially  for  hogs,  sheep, 
dairy  cows,  and  poultry.  The  six-rowed  barleys  are  regarded 
as  valuable  sorts  for  feeding.  The  hooded  varieties,  chiefly, 
are  grown  as  hay.  Barley  is  sometimes  grown  as  a  pasture 
crop,  as  a  nurse  crop  and  as  a  smother  crop.  A  pasture  crop  is 
used  for  grazing.  A  nurse  crop  is  a  temporary  one  often 
planted  with  a  forage  plant  such  as  clover  or  alfalfa  in  order 
to  secure  a  greater  return  from  the  land  the  first  year,  also  to 
inhibit  weed  growth,  and  to  prevent  the  blowing  or  washing 
of  the  soil.  A  smother  crop  is  used  to  prevent  the  growth  of 
weeds.  The  straw  of  barley  is  fed,  and  also  serves  as  a  bed- 
ding for  stock.  Malt  sprouts  and  "brewers'  grains"  are  now 
and  then  utihzed  as  stock  food. 

The  Brewing  Process.— Brewing  operations  vary  con- 
siderably in  the  different  countries,  and  with  the  character  of 
the  product.  The  brewing  materials  employed  are  malt, 
hops  and  water.  The  malt  is  made  from  germinating  barley, 
and  to  this  are  sometimes  added  unmalted  cereals  such  as 
corn,  wheat  and  rice. 

Malting. — In  this  process,  barley  is  prepared  for  brewing 
purposes.  The  barley  grains  are  steeped  for  about  forty- 
eight  hours  in  water,  and  then  spread  out  on  the  malting 
floor.  The  temperature  of  the  air  in  the  malting  room  is 
between  50  and  6o°F.  >  Germination  is  not  allowed  to  pro- 


150  BOTANY  OF  CROP  PLANTS 

ceed  to  the  point  when  the  young  shoot  (acrospire)  breaks 
out  from  under  the  lemma  and  palet,  but  the  process  is 
checked  by  transferring  the  germinating  grain  to  a  kiln 
where  it  is  kept  for  about  twelve  hours  at  a  temperature 
sufficient  to  thoroughly  dry  it  out.  During  germination, 
there  is  secreted  from  the  epithelial  layer  of  the  scutellum  a 
diastase  which  converts  the  starch  to  maltose  sugar.  Pep- 
tase  is  also  secreted  by  the  germinating  barley;  this  enzyme 
modifies  the  albuminoids  of  the  malt. 

Mashing. — The  malt,  prepared  as  above,  is  cleaned,  and 
crushed  in  a  roller  mill.  It  is  then  mixed  with  water,  and 
in  some  cases  with  unmalted  cereals.  The  mash  is  then  held 
at  the  proper  temperature  for  the  action  of  diastase  and  pep- 
tase,  which  chemically  invert  the  starch  into  maltose,  malto- 
dextrin  and  dextrin,  and  change  the  insoluble  albuminoids 
to  a  soluble  form. 

Boiling  the  Wort. — The  product  of  the  mashing  machine  is 
called  "wort."  During  the  boiling  process,  hops  are  added. 
Boiling  serves  not  only  to  extract  desirable  products  from 
the  hops,  but  to  render  harmless  certain  undesirable  con- 
stituents.    After  boiling,  the  wort  is  strained  into  coolers. 

Fermentation. — Yeast  is  now  added  to  the  wort.  This 
introduction  of  yeast  is  called  "pitching."  Through  the 
activity  of  yeast,  the  sugar  in  the  wort  is  changed  to  alcohol 
and  carbon  dioxide.  The  wort  has  been  changed  to  beer. 
It  is  removed  from  the  fermenting  vat,  stored  for  a  period  to 
allow  certain  products  to  settle,  and  also  to  permit  of  after- 
fermentation,  and  then  clarified,  filtered,  and  packed  for 
the  market. 

Production  ,of  Barley. — The  four  leading  countries,  in 
1915,  in  the  production  of  barley  were:  Russia,  United 
States,  Germany,  and  Austria-Hungary,  producing  respec- 
tively 475,109,000;  277,009,000;  150,000,000;  and  136,186,000 
bushels. 


HORDEUM 


151 


ACREAGE)  Production  and  Farm  Value  or  Barley  in  Various 
States,  191 5 


States 

Acres 

Bushels 

Farm  value,  Dec. 
I.  dollars 

North  Dakota 

1,400,000 

1,350,000 

1,360,000 

750,000 

656,000 

353.000 

270,000 

1,256,000 

44,800,000 
41,175,000 
39,440,000 
24,000,000 
23,288,000 
10,943,000 
8,370,000 
44,993,000 

19,712,000 
20,176,000 
24,453,000 
11,040,000 
13,041,000 
5,362,000 
3,515,000 
25,200,000 

California 

South  Dakota 

Wisconsin 

Kansas 

All  other  States 

United  States 

7,395,000 

237,009,000 

122,499,000 

References 

Atterberg,  a.:  Die  Erkennung  der  Haupt-varietaten  der  Gerste  in  den 

Nordeuropaischen   Saat-  und  Malzgerstan.    Landw.  Versuchstat.,  36: 

23-27,  1889. 
Die  Varietaten  und  Formen  der  Gerste.    Jour.  Landw.,  47:  1-44,  1899. 
Brenchley,  Winifred  E.:  Development  of  the  Grain  of    Barley.     Ann. 

Bot.,  26:  903-928,  1912. 
Broili,    J.:  tJber    die    Unterscheidung    der    zweizeiligen    Gerste-Hordeum 

distichum-am  Korne.     Inaug.  Diss.  Univ.  Jena,  1906. 
Das  Gernstenkorn  im  Bilde.     Stuttgart,  1908. 
Brown,  H.  T.,  and  Escombe,  F.:  On  the  Depletion  of  the  Endosperm  of 

Hordeum   Vulgare  during   Germination.     Proc.   Roy.   Soc.    (London), 

63: 3-25,  1898. 
Fruwirth,  C.  :  Das  Bliihen  der  Gerste.     Fiihling's  Landw.  Ztg.,  S.  544, 1906. 
Harlan,  Harry  V.:  Some  Distinctions  in  Our  Cultivated  Barleys,  with 

Reference  to  Their  Use  in  Plant  Breeding.     U.  S.  Dept.  Agr.  Bull.  137, 

1-38,  1914. 
Henning,  E.:  Beobachtungen  iiber  das  Bliihen  der  Gerste  (Schwedisch). 

Bot.  Notiser.,  1905. 
Hummel,   A.:  Die  botanischen  Unterscheidungsmerkmale  bei  zweizeiliger 

Gerste.     Illus.  Landw.  Ztg.,  830-839,  1909. 
Johannsen,    W.:  Entwickelung    und    Konstitution    des    Endosperms    der 

Gerste.     Ztschr.  Gesam.  Brauw.,  1905. 
Kraus,  C:  Die  Gliederung  des  Gersten-  und  Haferhalmes  und  deren  Bezie- 

hungen  z'u  den  Fruchtstanden.     Beiheft  I  der  Naturwis.  Ztsch.  fur 

Land-  und  Forstwirthschaft.     Munchen,  1905. 


152  BOTANY  OF  CROP  PLANTS 

Mann,  Albert,  and  Harlan,  H.  V. :  Morphology  of  the  Barley  Grain  with 

Reference  to  its  Enzyme-secreting  Areas.     U.  S.  Dept.  Agr.  Bull.  183: 

1-32,  1915. 
QuANTE,  Hugo:  Die  Gerste,  ihre  botanischen  und  brautechnischen  Eigen- 

schaften  und  ihre  Anbau.     Berlin,  1913. 
RiMPAU,  W. :  Die  genetische  Entwicklung  der  verschiedenen  Formen  unserer 

Saatgerste.    Landw.  Jahrb.,  21:  699-702,  1892. 
ScHULZ,  A.:  Die  Geschichte  der  Saatgerste.     Ztschr.  Naturw.,  83:  197-233, 

1912. 
Die  Abstammung  der  Saatgerste,  Hordeum  sativum  l-II.     Mott.  Naturf. 

Gesell.  Halle,  i:  18-27,  191 2. 
TscHERMAK,  E. :  Die  Bliih-  und  Fruchtbarkeitsverhaltnisse  bei  Roggen  und 

Gerste  und  das  Auftreten  von  Mutterkorn.     Fiihling's  Landw.  Ztg., 

S.  194,  1906. 
Voss,  A.:  Versuch  einer  neuen  Systematik  der  Saatgerste.     Jour.  Landw., 

33:  271-282,  1885. 
ZoBL,  A.,  and  Mikosch,  C.:  Die  Funktion  der  Grannen  der  Gerstenahre, 

Zitzber.  Akad.  Wiss.  (Vienna)  Math.  Naturw.  KL,  loi:  Abt.  i,  1033- 

1060,  1892. 


CHAPTER  XIII 
SECALE  CEREALE  (Rye) 

Habit  of  Plant,  Roots. — Rye  is  an  annual.  It  is  reported, 
however,  that  rye  stubble  in  a  field  may  sprout  after  long 
standing,  or  that  close  pasturing  for  a  season  may  cause  it 
to  live  through  a  second  winter.  This  is  no  doubt  a  reversion 
to  the  perennial  habit  displayed  by  the  species  from  which 
our  cultivated  rye  came. 

Rye  throws  out  a  whorl  of  four  primary  roots,  thus  differ- 
ing from  the  other  cereals.  The  root  system  branches  pro- 
fusely in  the  first  foot  of  soil  and  extends  to  a  depth  of  4  or 
5  feet. 

Stems,  Leaves. — As  compared  with  wheat,  oats  and  barley, 
the  stems  of  rye  are  tougher,  slenderer,  and  longer.  There 
are  commonly  five  to  six,  rarely  four  to  seven  stem  joints. 
The  leaves  are  similar  to  those  of  wheat.  The  ligule  is  short 
and  somewhat  rounded.  The  auricles  are  white,  narrow  and 
wither  early;  sometimes  they  are  absent  altogether. 

Inflorescence. — This  is  a  spike.  It  is  usually  somewhat 
longer  than  the  wheat  spike,  and  is  rather  uniformly  four- 
rowed.  There  are  from  20  to  30  rachis  joints.  There  is  a 
single  spikelet  at  each  joint.  All  the  spikelets,  from  base 
to  tip,  are  fertile.     The  spikes  have  no  terminal  spikelet. 

Spikelet. — Each  spikelet  (Fig.  55)  consists  of  three  flowers. 
The  two  lateral  flowers  mature  grains,  the  middle  one  aborts. 
The  glumes  are  very  narrow;  the  lemma  is  broad,  keeled, 
and  bears  a  long,  terminal  awn;  the  keel  is  strongly  barbed; 
the  palet  is  thin,  blunt  and  two-keeled.  The  lodicules  are 
IS3 


154 


BOTANY   OF   CROP   PLANTS 


small,  membranous,  and  ciliate  on  the  upper  margins.  There 
are  three  stamens,  and  a  single  pistil  with  two  feathery 
stigmas. 

Opening  of  the  Flower,  Pollination  and  Fertilization.— 
Rye  is  the  only  common  cereal,  besides  corn,  that  is  regularly 
cross-fertilized.  These  two  cereals  cannot  be  self-fertiUzed 
without  a  reduction  in  vigor  and  productivity.     Apparently, 


Pjq    25 — Rye  (Secale  cereale).     A,  a  single  spikelet  at  a  joint  on  the 
rachis;  B,  grain,  external  view;  C,  grain  in  cross-section.     A,  X  2j4;  B  and  C, 

xs- 

no  ill  effects  result  from  self-fertilization  of  barley,  wheat  and 
oats.  According  to  some  observers,  the  pollen  of  rye  is  im- 
potent on  the  stigma  of  the  same  flower.  Fruwirth  notes  that 
the  flower  is  completely  closed  within  twenty-five  to  thirty 
minutes  after  it  begins  to  open,  providing  the  stigmas  re- 
ceive pollen.  In  case  the  stigmas  are  not  dusted,  the  flowers 
remain  open  much  longer.  Blooming  begins  between  5:00 
and  6 :  00  a.m.  and  continues  until  9 :  00  or  1 1 :  00  a.m.  Then 
blooming  decreases  throughout  the    afternoon,    becoming 


SECALE   CERE ALE  I 55 

more  rapid  again  in  the  evening.  The  first  flowers  to  open 
are  slightly  above  the  middle  of  the  spike.  It  has  been  ob- 
served that  the  flowers  of  rye  can  be  induced  to  open  by 
rubbing  with  the  hand,  or  by  other  mechanical  stimulation. 

Maturing  of  Grain,  and  Mature  Grain. — The  anatomical 
structure  of  the  ovary  at  blooming  time  is  similar  to  that  of 
wheat,  as  are  also  the  changes  which  take  place  in  the  grain 
during  its  ripening. 

The  mature  grain  (Fig.  55)  is  free  from  the  lemma  and 
palet.  It  is  long,  narrow,  and  usually  darker  in  color  than 
wheat.  The  cross-section  of  the  mature  grain  shows  layers 
similar  to  those  in  wheat,  although  different  from  it  in  details. 

Rye  protein  usually  forms  about  6  to  12  per  cent,  of  the 
grain.  Gluten  is  present  in  the  protein,  hence,  the  flour  may 
be  made  into  porous  bread.  It  wfll  be  recalled  at  this  point 
that  of  the  common  small  cereals,  wheat  and  rye  possess  glu- 
ten, while  oats  and  barley  do  not.  The  flour  from  rye  is 
more  starchy  than  that  from  wheat. 

Germination  of  Rye. — Under  favorable  conditions,  germi- 
nation will  take  place  in  thirty-six  to  forty-eight  hours.  The 
optimum  germinating  temperature  is  77°F.,  maximum  87°F., 
and  minimum  33. 8°F.,  to  35.6°F. 

By  deep  seeding,  rye  may  send  out  roots  and  tillers  at  the 
second,  third,  or  even  fourth  node.  As  a  result  rye  can  be 
planted  deeper  than  wheat.  The  coleoptile  is  closed;  the 
first  leaf  is  rolled  and  brownish-red,  which  color  distinguishes 
the  rye  seedling  from  other  cereals. 

Classification,  and  Origin  of  Rye.— The  cultivated  sorts  of 
rye  all  belong  to  the  one  species,  Secale  cereale.  This  origi- 
nated from  Secale  anatolicum,  one  of  the  subspecies  of  S. 
montanum.  This  stem  form  differs  from  S.  cereale  in  the 
fragile  rachis,  the  smaller,  narrower  fruit,  and^  perennial 
rootstock. 

Environmental  Relations. — Rye  is  adapted  to  colder  and 


156  BOTANY   OF   CROP   PLANTS 

drier  climates  than  wheat,  and  will  thrive  on  poorer  soils 
and  more  sandy  soils  than  any  of  the  other  cereals. 

Uses  of  Rye. — Rye  flour  is  made  into  bread.  A  few  break- 
fast foods  include  rye  as  a  minor  component.  Mixed  with 
barley,  or  corn,  or  shorts,  or  oats,  rye  grain  is  fed  to  stock. 
In  some  sections  it  is  grown  for  hay,  or  as  a  pasture  crop,  and 
now  and  then  as  green  manure.  The  straw  finds  consider- 
able use  as  a  stable  bedding,  as  a  packing  material  for  nursery 
stock,  as  a  stuffing  for  horse  collars,  and  it  is  also  used  inthe 
manufacture  of  paper,  strawboard,  hats,  and  other  coarse 
straw  articles. 

Production  of  Rye. — Russia  produced  861,097,000  bushels 
of  rye  in  1915;  Germany  ranked  second,  with  470,000,000 
bushels,  Austria-Hungary  third,  with  154,075,000  bushels, 
and  the  United  States  fourth,  with  49,190,000  bushels. 
The  five  leading  States  in  the  order  of  their  production  for 
the  year  191 5  are  Wisconsin,  Michigan,  Minnesota,  Pennsyl- 
vania, and  Nebraska. 

References 

Batalin,  a.:  Das   Perennieren   des   Roggens.     Acta.  Horti.  Petropolitani, 

11:299-303,  1890.  Also  Verhandl.  Bot.  Ver.  Brand.,  32:29-32,  1891. 
RiMPAU,  W.:  Die  Selbst  Sterilitat  des  Roggens.  Landw.  Jahrb.,  6,  1877. 
ScHULZ,  August.:  Die  Geschichte  des  Roggens.     Jahresbericht  des  West- 

falischen  Provinzial-Vereins  fiir  Wissenschaft  und  Kunst  (zu  Miinster) 

fiir  1910-1911,  39:153-163,  1911. 
Beitrage  zur  Kenntnis  der  kultivierten  Getreide  und  ihrer  Geschichte,  I. 

Die  Abstammung  des  Roggens.     Zeitschr.  Naturw.,  84:339-347,  1913. 
TscHERMAK,   E.:  tjber  kunstliche   Auslosung   des    Bliihen    beim    Roggen. 

Ber.  Deut.  Bot.  Gesell.,  22:445-449,  1904. 
Das    BlUhen   des    Roggens    (Secale  cereale).     Ostrk.  Landw.     Wchnbl., 

1906,  p.  163. 
Die  Bluh-  und  Fruchtbarkeitverhaltnisse  bei  Roggen  und  Gerste  und  das 

Auftreten  von  Mutterhorn.     Fuhlings  Landw.  Ztg.,  55:194-199,  1906. 
Ulrich,  C:  Die  Bestaubung  und  Befruchtung  des  Roggens.     Inaug.  Diss., 

Jena,  1902. 
WiTTMACK,  L.:  tJber    die    Stammpflanze   des  gemeinen   Roggens,   Secale 

cereale.    Verhandl.  Bot.  Ver.  Brand.,  32:32-34,  1890. 


CHAPTER  XIV 
ZEA  (Cora,  Maize) 

Habit  of  Plant,  Roots. — Corn  is  distinctly  a  summer 
annual. 

The  root  system  is  fibrous.  Corn  generally  has  been  con- 
sidered a  shallow-rooted  plant.  The  contrary  is  the  case. 
At  maturity  the  roots  come  to  fill  the  upper  3  feet  of  soil  and, 
under  some  conditions,  may  reach  to  a  depth  of  4  or  5  feet 
(Fig.  56).  The  depth  of  planting  appears  to  bear  no  rela- 
tion to  the  depth  of  rooting,  for  the  first  whorl  of  roots  usu- 
ally forms  about  i  inch  below  the  soil  surface,  no  matter  how 
deep  the  seed  is  planted.  It  will  be  remembered  that  this 
is  true  for  the  other  cereals  too.  The  roots  of  corn  are  thrown 
off  in  whorls,  varying  in  number  from  two  to  ten,  one  whorl 
above  another.  The  internodes  between  whorls  are  very 
short.  The  entire  group  of  whorls  constitutes  the  root 
crown. 

Two  kinds  of  roots  are  developed  (Ten  Eyck):  {a)  main 
vertical  roots  and  {h)  main  lateral  roots.  Vertical  roots 
curve  out  slightly  from  the  crown  and  go  directly  downward. 
The  laterals  curve  downward,  as  they  leave  the  crown,  then 
extend  horizontally  for  a  distance,  finally  taking  a  downward 
course.  Laterals  that  leave  the  crown  at  about  the  soil 
level  slope  gradually  downward,  as  indicated  above.  Midway 
between  the  rows  of  planted  grain,  about  22  inches  from  the 
157 


158 


BOTANY   OF   CROP  PLANTS 


hill,  these  laterals  are  about  4  or  5  inches  below  the  soil  level. 
The  laterals  may  be  shallower  than  given,  in  heavy  soils 


ground  line 


Fig.  56. — A,  root  system  of  corn  (Zea  mays);  the  squares  are  one  foot  on  a 
side;  B,  prop  or  aerial  roots  of  corn.  (A,  redrawn  from  U.  S.  De-pt.  Agri,;  B, 
somewhat  modified  after  Bailey.) 


and  wet  seasons.     The  roots  of  most  plants  are  more  super- 
ficial in  a  heavy  or  wet  soil  than  in  a  light  and  drier  soil. 


ZEA  159 

This  is  quite  likely  a  response  to  oxygen  supply,  as  well  as  to 
moisture  supply.  The  amount  of  oxygen  in  the  soil  decreases 
as  the  depth  increases.  Moreover,  the  rate  of  decrease  is 
greater  in  heavy  or  wet  soils  than  in  light  or  dry  soils.  When 
it  is  understood  that  every  living  root  cell  derives  its  oxygen 
for  respiration  from  the  soil  air  immediately  surrounding 
and  that  the  oxygen  does  not  diffuse  to  any  extent  from  the 
aerial  parts  of  the  plant  down  through  the  stem  to  the  roots, 
we  see  the  probable  explanation  of  the  fact  that  a  shallow 
root  system  is  peculiar  to  a  heavy  or  wet  soil.  In  this  con- 
nection, it  should  be  stated  that  an  important  result  of  tillage 
is  the  loosening  of  the  soil  so  that  oxygen  may  more  easily 
diffuse  to  the  roots  of  the  plant.  All  main  roots  give  off 
numerous  finer  branches  and  these  in  turn  branch,  so  that  at 
maturity  there  is  an  interlacing  mass  of  roots  in  the  soil. 
Fully  two-thirds  of  the  entire  root  system  occurs  in  the  first 
4  inches  of  soil.  This  statement  is  based  on  records  of 
a  number  of  observers  (Sturtevant,  Hunt,  Newman,  Ten 
Eyck,  Hays).  Ten  Eyck  has  observed  that,  although  the 
main  laterals  are  several  inches  below  the  soil  surface,  they 
may  send  upward  finer  branches  to  within  3^  inch  of  the  sur- 
face. The  depth  of  the  corn  roots  determines  the  depth  of 
cultivation.  If  it  is  so  deep  as  to  destroy  roots,  the  yield 
is  decreased. 

"Prop"  or  "Brace"  Roots. — In  addition  to  the  ordinary 
underground  roots,  corn  develops  aerial  roots,  the  so-called 
"prop"  or  "brace"  roots  (Fig.  56).  These'  arise  in  whorls 
at  successive  levels  above  the  surface,  extending  obliquely 
downward.  They  are  covered  with  a  mucilaginous  sub- 
stance which  protects  them  from  drying  out.  As  aerial 
roots,  they  are  unbranched,  but  they  branch  profusely  when 
they  strike  the  soil.  They  have  the  role  of  absorption,  then, 
as  well  as  anchorage. 


l6o  BOTANY  OF  CROP  PLANTS 

Stem. — Corn  is  the  largest  of  the  common  cereals.  How- 
ever, no  other  cereal  varies  so  in  size.  There  are  dwarf  forms 
scarcely  3  feet  high,  while  some  are  15  or  more  feet  high. 
The  stem  is  jointed  as  in  all  grasses.  The  internodes,  how- 
ever, are  not  hollow,  but  are  filled  with  a  soft  pith  through 
which  run  numerous  vascular  bundles,  the  fibers.  The 
nodes  are  solid  as  in  other  grasses.  The  internodes  are 
furrowed  on  the  side  next  the  leaf  blade.  The  corn  plant 
produces  '^ suckers^'  which  correspond  to  the  "stools"  of 
wheat,  as  to  their  morphology.  "Suckers"  are  secondary 
stems  or  branches  arising  from  the  lower  nodes.  These 
branches  develop  their  own  roots.  "Suckers"  of  corn  are 
undesirable,  for  they  do  not,  as  a  rule,  produce  ears,  although 
they  are  heavy  soil  "feeders." 

Leaves. — The  leaves  are  arranged  alternately  on  opposite 
sides  of  the  stem  as  in  all  grasses.  They  vary  in  number  from 
8  to  20.  The  blade  is  long  and  flat;  the  ligule  closely  invests 
the  stalk,  acting  as  a  rain-guard.  Water  that  runs  down  the 
stem  and  leaf  blade  is  prevented  from  entering  the  space 
between  the  culm  and  leaf  sheath  by  this  tightly  fitting 
ligule. 

The  corn  leaf  is  thrown  into  a  number  of  folds  along  the 
edges  and  at  the  base.  This  is  due  to  the  more  rapid  growth 
of  the  cells  at  these  points.  The  corn  plant  is  moderately 
well  adapted  to  dry  conditions.  An  examination  of  the 
leaf  structure  explains  this.  On  the  upper  surface  of  the 
leaf  blade,  along  either  side  of  the  midrib,  are  a  number  of 
large  wedge-shaped  cells;  these  absorb  water  readily  in  moist 
weather,  become  turgid,  and  thus  flatten  the  leaf  out.  In 
dry  weather,  these  cells  lose  their  turgor.  Hence  the  leaf 
rolls  up,  presenting  a  smaller  evaporating  surface.  In  addi- 
tion to  this  adaptation  to  dry  conditions,  the  cuticle  of  the 
lower  surface  of  the  leaf  is  much  thickened,  and  the  water 


ZEA 


l6l 


requirement  of  the  plant  is  low  as  compared  with  oats, 
clover,  or  alfalfa.  It  has  been  computed  that  an  average 
acre  of  well-adapted  corn,  grown  at  the  Nebraska  Agricul- 


FiG.   57.      Pistillate  and  staminate  inflorescences  of  corn  (Z 


ea  mays). 


tural  Experiment  Station,  has  4  acres  of  leaf  space,  counting 
both  sides. 
Inflorescence.— Ordinarily,    corn   is   monoecious,   that  is. 


l62 


BOTANY  OF  CROP  PLANTS 


the  stamens  and  pistils  are  borne  in  separate  inflorescences  on 
the  same  plant  (Fig.  57).  The  staminate 
tlowers  are  in  a  panicle  at  the  top  of  the 
stalk;  this  inflorescence  is  known  as  the 
'Uassel."  The  pistillate  flowers  are  borne 
in  a  spike  which  is  placed  in  the  axil  of  a 
leaf  lower  down  on  the  stem.  When  mature, 
the  pistillate  inflorescence  is  called  the  ''ear." 

Staminate  Inflorescence  ("tassel"). — The 
rachises  of  the  panicle  are  long,  slender,  and 
spike-hke.  One  may  distinguish  between  the 
central  and  lateral  spikes  of  the  panicle.  In 
the  central  spike  (Fig.  58),  there  are  usually 
from  four  to  eleven  rows  of  spikelets,  in  pairs. 
Lateral  branches  usually  have  only  two  rows 
of  spikelets,  in  pairs.  One  spikelet  of  each 
pair  is  pedicellate,  the  other  sessile  (Fig.  59), 
or  in  some  cases  both  may  be  sessile.  The 
groups  of  spikelets  may  overlap. 

Staminate  Spikelet. — Each  normal  stami- 
nate spikelet  bears  two  flowers,  each  produc- 
ing three  perfect  stamens  and  a  rudimentary 
pistil  (Fig.  60).  The  glumes  are  seven-  to 
twelve-nerved,  and  about  equal  in  size.  The 
lemma  is  three-  to  iive-nerved  and  the  palet 
two-nerved.  The  two  lodicules  are  fleshy 
and  truncate.  The  anthers  are  long.  The 
upper  flower  of  a  spikelet  matures  first;  its 
palet  is  larger  than  the  lemma,  while  in  the 
lower  flower,  the  lemma  is  larger  than  the 
palet. 

Pistillate  Inflorescence  ("ear")  General 
—The    ear    (Fig.    61)    is   borne   on    a   short 


Fig.  58.-  a 
single  branch  of 
the  staminate  in- 
florescence  of 
corn  (Zea  mays). 

Characteristics. 


ZEA  163 

branch,  the  so-called  "shank."  This  branch  consists  of  a 
number  of  very  short  internodes  with  one  modified  leaf  at 
each  node.      The  blades  of  the  modified  leaves  have  been 


6pikelet 


Fig.  59. — A  pair  of  staminate  spikelets  of  corn  (Zea  mays). 

reduced,  the  leaf  sheaths  alone  remaining.  The  collection 
of  leaf  sheaths  on  the  shank  forms  the  "husk"  of  the  ear. 
The  pistillate  spikelets  are  arranged  in  rows  along  a  fleshy 
axis,  the  "cob." 


164 


BOTANY   OF   CROP   PLANTS 


What  Is  the  "Ear,"  Morphologically? — There  are  two 
theories  as  to  the  morphology  of  the  ear  of  corn.  The  view 
of  Hackel  and  of  Harshberger  is  that  the  ear  is  the  result  of 
a  fusion  of  a  number  of  two-rowed 
pistillate  spilces.  Since  each  spikelet  is 
two-flowered,  and  the  lower  abortive, 
there  are  often  formed  the  two  distinctly 
paired  rows.  The  cob  is  said  to  be 
formed  by  the  fusion  of  separate  rachises. 
Opposed  to  the  above  theory  is  that  of 
Montgomery,  who  holds  that  the  ear 
develops  "directly  from  the  central 
spike  of  some  tassel-like  structure 
similar  to  the  well-known  corn  tassel." 
His  evidence  for  this  beHef  may  be 
summarized  as  follows : 

1.  He  has  found  tassels  in  which  a 
few  pistillate  flowers  were  found  on  the 
central  spike,  also  tassels  in  which  the 
central  spike  had  developed  into  a  fair- 
sized  ear  of  corn. 

2.  He  observed  a  case  in  which  the 
lateral  spikes  as  well  as  the  central  one 
had  developed  pistillate  flowers,  form- 
ing a  number  of  four-rowed  "nubbins" 
surrounding  a  central  well-developed 
twelve-rowed  ear. 

3.  The  central  spike  develops  pistil- 
late flowers  much  more  readily  than  the 
lateral  ones  of  the  tassel.     The  central 

spike  has  the  greater  number  of  rows  of  spikelets. 

4.  He  has  observed  the  development  of  pistillate  flowers 
from  staminate  ones.     This  development  is  as  follows: 


Fig.  60. — Longitudinal 
section  of  staminate 
spikelet  of  Country  Gen- 
tleman sweet  corn,  X  1 5 . 
G,  glume;  Pa,  palet;  An, 
position  of  one  of  the 
lateral  anthers;  L,  lem- 
ma; A,  dorsal  anther. 
P,  rudimentary  pistil;  /, 
joint  of  rachilla.  (After 
Weatherwax.) 


ZEA  165 

(a)  Pedicellate  spikelet  shortens  and  becomes  sessile;  the 
difference  between  the  two  flowers  of  this  becomes  greater. 

(b)  The  lower  glume  shortens  and  thickens. 


Fig.   6r.- — Corn  (Zca  mays).      Young  pistillate  infLjrescence  ("ear"),  showing 
the  long  styles  ("silks"). 

(c)  Lemma  and   palet  of  upper  flower  become   reduced 
while  the  lower  flower  becomes  abortive. 

(d)  Sessile  flower  becomes  pistillate. 

(e)  Both  flowers  become  pistillate. 


l66  BOTANY  OF  CROP  PLANTS 

Recently  East  and  Hayes  have  expressed  an  opinion  very 
similar  to  that  of  Montgomery.  Quoting  from  them,  "The 
ear  of  maize,  then,  is  a  meristic  variation  produced  from  the 
central  spike  of  the  tassel  of  the  lateral  branches  of  teosinte 
or  of  a  teosinte-like  plant,  and  not  a  fusion  of  the  lateral 
spikelets."  Montgomery  suggests  that  teosinte  and  corn 
had  a  common  ancestor,  which  was  a  "large,  much-branched 
grass,  each  branch  being  terminated  by  a  tassel-Hke  structure, 


J^  glume 


lemma  of 

ferhle  ' 

jlower 

^Znd  ^lume 
Fig.  62. — Pistillate  spikelet  of  corn,  much  enlarged.     {After  Necs.) 

bearing  hermaphrodite  flowers."  He  says  further:  "As 
evolution  progressed,  the  central  tassel  came  to  produce  only 
staminate  flowers,  these  being  higher  and  in  a  better  position 
to  fertilize  the  flowers  on  the  lower  branches.  At  the  same 
time,  the  lateral  branches  came  to  produce  only  pistillate 
flowers,  their  position  not  being  favorable  as  pollen  producers, 
while,  on  the  contrary,  they  were  favorably  placed  to  receive 
pollen.  This  differentiation  in  the  flowers  was  accompanied 
by  a  shortening  of  the  internodes  of  the  lateral  branches  until 
they  were  entire!}-  enclosed  in  the  leaf  sheaths"  (the  husks). 
Pistillate  Spikelet. — Each  normal  pistillate  spikelet  has  two 


ZEA 


167 


flowers,  the  lower  one  of  which  is  abortive^  (Figs.  62  and  63). 
The  palet  and  lemma  of  the  abortive  flower  remain,  and  form 
a  part  of  the  "chaff"  on  the  cob.     The  spikelet  is  subtended 


Fig.  63. — Longitudinal  section  of  pistillate  spikelet  of  Black  Mexican 
sweet  corn,  X  25.  Sti,  base  of  stigma;  Sty,  style;  E,  outline  of  embryo  sac; 
L,  lemma;  Pa,  palet;  St,  stamen  of  aborted  flower;  Sc,  stylar  canal;  Ov,  func- 
tional ovule;  G,  glume;  Sta,  rudimentary  stamen;  P,  pistil  of  aborted  flower; 
J,  joint  of  rachilla.     (After  Weatherwax.) 


by  two  glumes  that  are  shorter  than  the  ovary,  very  broad 
and  fleshy  at  the  base,  thin  membranous  above  and  fringed 

^  Stewart  has  noted,  in  the  Country  Gentleman  variety  of  corn,  that  some 
spikelets  bear  two  well-developed  ^flowers  inside  each  pair  of  glumes.  He 
further  points  out  that  the  irregularity  in  the  arrangement  of  grains  on  the 
ear  may  be  due  to  the  development  of  the  second  flower  in  some  of  the  spike- 
lets,  which  tends  to  throw  some  of  the  grains  out  of  line.  The  same  has  been 
noted  by  Sturtevant  and  Kempton. 


1 68  "  BOTANY  OF  CROP  PLANTS 

on  the  edges.  The  lemma  and  palet  of  the  fertile  flower  are 
short,  broad  and  membranous.  In  pod  corn,  glumes,  lemma, 
and  palet  attain  a  considerable  size  and  enclose  the  grain. 
The  single  ovary  bears  one  long  style,  the  corn  "silk,"  which 
is  forked  at  the  tip.  It  is  well  to  remember  that  there  is  one 
silk  for  each  grain  on  the  cob.  Weatherwax  considers  the 
corn  silk  a  compound  stigma  rather  than  a  style.  The  silk 
is  indeed  receptive  to  pollen  a  good  portion  of  its  length, 
possibly  all.  A  hot,  dry  wind  may  wither  the  silks,  thus 
destroying  their  receptivity  to  p|ollen.  FertiUzation  of  the 
ovules  consequently  does  not  take  place,  and  the  ovules  do 
not  mature.  The  short  protuberance  at  the  top  of  the  ovary 
is  considered  by  Weatherwax  to  be  the  style.  It  is  traversed 
by  a  canal,  the  stylar  canal.  Three  small  rudimentary 
stamens  have  been  observed  by  Baillon,  and  Weatherwax,  in 
the  fertile  flower;  the  lodicules  are  absent.  The  small 
aborted  flower  has  rudimentary  stamens  and  pistil  about 
equally  developed;  the  lodicules  are  present. 

Hermaphroditic  Flowers. — Ordinarily  in  corn  the  flowers 
are  imperfect,  that  is  either  staminate  or  pistillate.  Perfect 
or  hermaphroditic  flowers  sometimes  occur,  however.  Herma- 
phroditic flowers  are  far  more  common  on  the  tassel  than  on 
the  ear.  East  and  Hayes  record  a  sterile  dwarf  mutation 
which  had  nothing  but  hermaphroditic  flowers.  Hermaphro- 
ditic flowers  have  the  stamens  reduced.  Lodicules  are  well 
developed  in  staminate  flowers,  reduced  in  hermaphroditic 
flowers,  and  altogether  absent  in  fertile  pistillate  flowers. 
Montgomery  observed  hermaphroditic  flowers  on  normal 
types  of  ears.  The  plants  from  these  seeds  came  true  to 
type.  The  seed  was  normal  in  every  respect  except  that  it 
had  three  fully  developed  stamens  coming  from  near  the 
base  of  the  ovary.  There  were  also  three  small  stamens  in 
the  aborted  flower  of  each  pistillate  spikelet.     The  plants 


ZEA  169 

were  of  unusual  appearance,  being  5  feet  high,  with  short 
internodes  and  broad  leaves. 

Opening  of  the  Flowers,  and  Pollination. — Cross-pollina- 
tion, consequently  cross-fertilization,  is  the  rule  in  corn  but 
self-fertihzation  frequently  occurs.  Wind  and  gravity  are 
the  chief  factors  in  pollen  dissemination,  although  bees 
visit  the  flowers  and  are  evidently  concerned  in  pollen 
dispersal;  they  are  relatively  of  far  less  importance  than 
wind. 

In  the  case  of  the  staminate  inflorescence,  the  first  flowers 
to  open  are  those  near  the  upper  part  of  the  central  spike; 
blooming  spreads  both  upward  and  downward,  more  rapidly 
downward.  The  same  order  of  blooming  occurs  on  the 
branches  of  the  tassel. 

The  time  of  pollen  shedding  depends  upon  weather  con- 
ditions. Cold,  wet,  weather  retards  or  even  prevents  the 
shedding  of  pollen.  On  the  other  hand,  droughty  conditions 
hasten  the  shedding  of  pollen,  but  delay  the  appearance  of 
silks.  Hence  it  may  happen  that  under  these  conditions 
much  of  the  pollen  is  scattered  before  the  stigmas  are  pro- 
truded and  receptive,  and  an  incomplete  filling  of  the  ear 
results.  On  sunshiny  days,  most  of  the  pollen  is  shed  during 
the  forenoon  and,  in  some  instances,  late  in  the  afternoon  of 
the  same  day.  Individual  tassels  usually  remain  in  blossom 
from  four  to  ten  days  or  even  more,  depending  upon  the 
weather.  Furthermore,  the  anther  does  not  shed  all  its  pollen 
as  soon  as  it  opens,  but  discharges  it  a  little  at  a  time.  In 
investigating  a  number  (59)  of  varieties  of  corn  as  to  the 
time  elapsing  between  the  appearance  of  anthers  and  appear- 
ance of  first  silks,  Gernert  finds  marked  variation.  Both 
dichogamy  (maturation  of  pollen  and  stigmas  at  different 
times)  and  homogamy  (simultaneous  maturity  of  pollen  and 
stigmas)  may  occur.     Furthermore,  in   dichogamous  indi- 


1 70  BOTANY  OF  CROP  PLANTS 

viduals,  protandry  (anthers  mature  first)  or  protogyny 
(stigmas  mature  first)  may  occur.  Out  of  2,794  individuals 
in  59  varieties  examined,  he  found  243  individuals  homoga- 
mous,  92  protogynous,  and  2,459  protandrous.  It  appears, 
then,  that  protandry  is  the  rule  in  corn.  In  protandrous 
individuals,  the  first  appearance  of  silks  occurred  from  one  to 
twenty-three  days  after  pollen  shedding,  although  the  aver- 
age is  two  days.  Varieties  of  corn  dealt  with  in  the  above 
were  pod,  pop,  flint,  dent,  soft,  and  sweet.  Collins  records 
the  discovery  of  the  protogynous  habit  in  a  variety  of  maize 
introduced  from  Granada,  Spain.  Ordinarily,  however, 
dichogamy  is  seldom  pronounced  enough  to  completely  ex- 
clude self-pollination. 

Gernert  has  also  made  observations  as  to  the  number  of 
days  intervening  between  the  appearance  of  tassel  and 
anthers.  He  finds,  out  of  3,319  individuals  in  57  varieties, 
that,  in  the  greatest  number  (514),  the  anthers  appeared 
nine  days  after  the  tassel,  and  that  in  more  than  half  of 
the  individuals  the  first  anthers  appeared  in  seven  to  ten 
days  after  the  tassels  bearing  them  appeared. 

Pollen  is  produced  in  great  quantities.  It  is  estimated 
that  each  tassel  produces  20,000,000  to  50,000,000  grains  of 
pollen.  Lazenby  estimated  that  for  each  ovule  in  dent 
maize  there  are  about  45,000  pollen  grains  produced. 

The  size  of  pollen  grains  in  corn  varies.  Pollen  produced 
by  central  spikes  is  larger  than  that  produced  by  laterals. 
Livingston  observed  that  in  Leaming  corn  the  pollen  grains 
from  the  central  spikes  were  0.02  milKmeter  larger  on  the 
average  than  those  from  lateral  spikes.  Of  12  varieties 
examined,  Gernert  finds  that  the  average  diameter  of  the 
pollen  grain  of  corn  varies  from  0.08  to  o.i  millimeter. 
They  are  rather  ellipsoidal  in  shape.  Corn  pollen  soon 
shrivels  after  being  shed,  but  its  germinating  power  is  not 


ZEA  171 

destroyed  by  this.  However,  pollen  does  not  remain  viable 
much  longer  than  twenty-four  hours  after  shedding. 

Corn  "silks"  are  long  and  plumose.  The  first  silks  to 
appear  on  the  ear  are  those  from  grains  slightly  above  the 
base.  Generally,  four  or  five  days  intervene  between  the 
appearance  of  lowest  and  uppermost  silks.  Hence,  it  will 
require  four  or  five  days  to  polhnate  all  the  silks  of  an  ear. 
Unfavorable  cHmatic  conditions,  such  as  cold,  wet  weather 
or  extremely  hot  days,  may  account  for  the  incomplete 
"filling  out"  of  ears. 

The  silks  are  receptive  throughout  their  length.  Best 
results  are  obtained  when  silk  receives  the  pollen  within  a 
few  days  after  its  emergence  from  the  husk.  Silk  exposed 
by  splitting  down  the  husks  proved  receptive.  Again, 
fertilization  is  not  prevented  when  tips  of  silks  are 
cut  off. 

Fertilization,  and  Development  of  the  Grain. — Just  prior 
to  fertilization,  the  ovary  of  corn  is  bent  from  the  perpendic- 
ular so  that  the  silk,  instead  of  pointing  directly  out  from 
the  cob}  points  in  a  direction  longitudinal  to  the  cob.  The 
ovary  is  on  a  stalk  (rachilla)  about  2.5  millimeters  long.  The 
ovule  almost  fills  the  ovary  cavity.  It  is  attached  to  the 
wall  of  the  ovary  by  more  than  one-third  its  circumference. 
The  outer  integument  is  incomplete  while  the  inner  covers 
the  entire  ovule,  except  the  micropyle.  This  opening  is  just 
above  the  point  of  attachment  of  the  lemma. 

The  ovary  wall  at  this  time,  that  is  before  fertilization, 
possesses  the  following  coats: 

1.  Smgle  row  of  epidermal  cells. 

2.  Many  layers  of  parenchyma  tissue,  varying  somewhat  in 
size. 

3.  Single  layer  of  inner  epidermal  cells. 

True  records  the  presence  of  a  pit  "a  short  distance  from 


172  BOTANY  OF  CROP  PLANTS 

the  base  of  the  style,  on  the  posterior  side."  This  is  probably 
the  "stylar  canal"  described  by  Poindexter. 

The  outer  and  inner  integuments  vary  in  thickness  from 
two  to  four  layers.  The  very  large  embryo  sac  is  located  at 
the  base  of  the  nucellus. 

After  fertilization,  the  following  changes  take  place  in  the 
maturing  grain: 

1.  Outer  integument  disappears. 

2.  Cells  of  inner  integument  become  flattened,  due  to 
pressure  from  within. 

3.  The  middle  and  inner  cells  of  pericarp  become  compacted. 

4.  Cells  of  nucellus  disappear  to  a  large  extent. 

5.  Hardening  of  the  cell  walls  of  the  pericarp. 

6.  Fusion  of  pericarp  and  inner  integument. 

Xenia  in  Com. — ^Xenia  is  the  term  appUed  to  the  phe- 
nomenon in  which  some  character  of  the  male  appears  at 
once  in  the  seed.  For  example,  in  crossing  a  strain  of  corn 
having  yellow  endosperm  with  a  strain  having  white  endo- 
sperm, the  grains  produced  are  all  yellow  in  every  case,  no 
matter  which  is  used  as  the  male  parent.  Xenia  is- shown 
only  in  case  the  parent  having  yellow  endosperm  is  used  as 
the  male  parent.  The  yellow  endosperm  character  is 
dominant  over  white  endosperm.  Pollen  from  the  plant 
bearing  yellow  endosperm  will  carry  this  character;  pollen 
from  the  plant  bearing  white  endosperm  will  carry  the  white 
character.  When  pollen,  bearing  the  yellow  endosperm 
character,  is  placed  on  the  stigma  of  the  grain  having  white 
endosperm,  the  pollen  tube  will  discharge  into  the  ovule  two 
male  nuclei,  each  bearing  the  character  for  yellow  endosperm. 
One  sperm  nucleus  fuses  with  the  egg  nucleus,  the  other 
sperm  nucleus  fuses  with  the  two  polar  nuclei.  The  result 
of  this  triple  fusion  (second  sperm  nucleus  and  two  polar 
nuclei)  is  the  endosperm.     Now,  since  yellow  is  dominant, 


ZEA  173 

the  grain  that  is  formed  by  this  double  fertilization  will  have 
a  yellow  endosperm.  Thus  double  fertilization  explains 
the  phenomena  of  xenia.  It  is  of  course  true  that,  if  in  the 
above,  pollen  from  the  white  endosperm-bearing  plant  were 
used,  xenia  would  not  be  shown.  Xenia,  the  visible  effects 
of  double  fertilization,  has  been  found  in  the  following  con- 
spicuous cases  in  corn— in  each  case  below,  the  plant  men- 
tioned first  is  the  female : 

Non-starchy-seeded  plants   crossed  with   starchy-seeded 
plants  always  give  starchiness. 

Non-yellow  endosperm  crossed  with  yellow  shows  yellow. 

Non-colored    aleurone   layer    crossed   with   purple    gives 
purple. 

Non-colored  aleurone  layer  crossed  with  red  gives  red. 
/variation  in  the  Corn  Plant. — There  are  marked  individual 
differences  in  the  plants  of  an  ordinary  field  of  corn.  The 
plants  may  vary  in  height,  vigor,  leaf  production,  height  of 
ears  on  the  stalk,  shape  of  ears,  composition  of  kernel, 
etc.  Moreover,  there  is  scarcely  any  other  crop  plant  in 
which  we  find  more  abnormalities  or  monstrosities  than  we 
do  in  corn.  We  have  mentioned  hermaphroditic  flowers, 
both  in  the  tassel  and  ear  as  one  abnormality;  to  these  we 
may  add  branched  ears,  tassels  with  a  few  or  many  kernels, 
variegated  leaves,  and  variegated  ears.  In  corn  it  is  possible 
for  the  different  kernels  of  an  ear  to  receive  pollen  from  many 
different  plants,  and  from  its  own  tassel.  Hence,  it  usually 
happens  that  the  grains  on  the  same  ear  have  different 
hereditary  characters  as  shown  by  their  varied  progeny. 
This  is  well  shown  in  variegated  ears.  If  xenia  occurs,  the 
effects  of  this  crossing  may  be  evident  the  same  season.  For 
example,  if  pollen  from  dent  corn  fertilizes  some  of  the  ovules 
on  an  ear  of  sweet  corn,  those  ovules  appear  starchy,  while 
the  other  grains  of  the  ear  of  corn,  fertihzed  with  sweet  corn 


174 


BOTANY   OF   CROP   PLANTS 


pollen  are  wrinkled.  If  xenia  does  not  occur,  the  results  of 
the  mixing  will  not  show  up  until  the  second  year.  Hence, 
ordinarily  even  though  an  ear  of  corn  appears  uniform,  the 
separate  kernels  may  have  different  heredity.  The  only  way 
of  testing  its  purity  is  to  plant  the  grains  and  observe  their 
progeny.  Of  course  in  this  test,  care  must  be  taken  to  pre- 
vent strange  pollen  from  blowing  in.  This  is  practically  ac- 
compHshed  by  isolating  the  test  plots. 

Results  of  Self-fertilization  in  Corn. — If  our  ordinary 
field  strains  of  corn  are  self-fertiHzed  for  several  generations 
the  yield  is  considerably  reduced.  However,  as  a  result  of 
this  inbreeding,  we  may  be  sure  that  all  the  kernels  on  an  ear 


Fig.  64. — Corn  (Zea  mays).  ^,  median  lengthwise  section,  cut  parallel  to 
broad  surface,  of  grain  of  dent  corn;  B,  cross-section  of  same  through  the 
embryo;  C,  section  as  in  A  of  flint  corn. 


have  the  same  hereditary  qualities.  Furthermore,  artificial 
self-fertiHzation  for  five  or  more  successive  years  results  in  a 
strain  that  is  not  so  complex  in  its  characters,  that  is,  a  race 
which  is  comparatively  uniform  and  pure. 

The  Mature  Grain  of  Com. — The  mature  grain  of  corn 
varies  considerably  in  shape  (Fig.  64).     In  most  varieties, 


ZEA  175 

it  is  flattened  in  a  plane  at  right  angles  to  the  length  of  the 
cob.  The  broader  surface  is  roughly  triangular  in  outline, 
being  broader  above  than  at  the  base.  The  groove  indicates 
the  position  of  the  embryo.  At  the  "tip"  of  a  mature  grain, 
may  still  be  found  the  papery  remains  ("chaff")  of  the  palet, 
lemma,  and  glumes  of  the  pistillate  spikelets.  The  point  of 
the  grain,  where  it  was  attached  to  the  cob,  is  the  peduncle 
of  the  flower.  The  opposite  indented  end  of  the  grain  is 
often  marked  by  a  small  point  which  is  the  remnant  of  the 
style.  A  longitudinal  section  of  the  corn  grain  parallel  with 
the  broad  surface  will  show,  with  magnification,  the  follow- 
ing parts. 

1.  Pericarp,  of  several  layers. 

2.  Testa,  inner  integument,  of  two  layers. 

3.  Nucellar  tissue. 

4.  Aleurone  layer,  outermost  layer  of  endosperm,  a  single 
row  of  cells. 

5.  Starchy  endosperm. 

6.  Horny  endosperm. 

7.  Embryo. 

8.  Tip  cap. 

The  pericarp  and  testa  form  the  hull.  It  is  possible  to 
separate  mechanically  the  starchy  endosperm  into  two  parts, 
the  crown  starch  and  tip  starch. 

The  following  is  a  fair  average  of  the  relative  proportions 
of  the  divisions  of  the  grain,  as  given  by  Hopkins,  Smith, 
and  East: 

Per  cent. 

Embryo 11. o 

Tip  cap 1.5, 

"Hull" 6.0 

■     Aleurone  layer 8.0  to  14.0 

Horny  endosperm 45 .  o 

Starchy  endosperm 25.0 


176  BOTANY  OF  CROP  PLANTS 

Of  course,  there  is  a  marked  variation  in  the  proportions 
of  these  parts,  and  in  their  chemical  composition. 

Chemical  analysis  of  the  above  parts  shows'  that  the  hull 
contains  less  protein  (about  4  per  cent.)  than  any  other  part 
of  the  grain.  The  endosperm  is  richest  in  protein,  containing 
20  to  25  per  cent.  The  horny  endosperm  contains  about 
go  per  cent,  starch  and  10  per  cent,  protein.  The  starchy 
endosperm  is  poor  in  total  amount  of  protein  (5  to  8  per 


Fig.  6«;. — Variation  in  the  shape  of  corn  grains.     Which  is  the  best  propor- 
'tioned  kernel?     Why?     (After  Mich.  Agr.  Exp.  Sta.  Bull.  34-) 

cent.).  The  germ  is  rich  in  oil,  being  composed  of  about  35 
to  40  per  cent,  of  oil  and  19  to  20  per  cent,  protein.  As 
much  as  80  to  85  per  cent,  of  the  total  oil  content  of  the  kernel 
occurs  in  the  embryo. 

In  high-protein  corn  kernels,  the  horny  endosperm  ex- 
tends up  to  and  comes  into  contact  with  the  embryo, 
the  tip  starch  being  entirely  separated  by  it  from  the  crown 
starch.  In  low-protein  corn  kernels,  the  amount  of  horny 
endosperm  is  reduced,  tip  and  crown  starch  being  continuous 
between  it  and  the  embryo.  The  embryo  is  much  larger  in 
high-oil  kernels  than  in  low-oil  kernels. 


ZEA  177 

Embryo. — In  the  normal  flower,  the  embryo  of  corn  is  on 
the  side  of  the  grain  toward  the  tip  of  the  ear.  Inverted 
grains  have  been  found,  however.  This  inversion  is  due  to 
the  development  of  the  lower  flower  of  the  pair  in  the  pistil- 
late spikelet.  The  embryo  has  the  same  structure  as  that 
of  wheat.  On  account  of  its  large  size,  the  parts  are  readily 
made  out.  Its  structure  is  best  studied  in  a  longitudinal 
section  cut  at  right  angles  to  the  broad  surface.  The  pri- 
mary root  is  conspicuous;  the  two  laterals  may  be  recognized 
as  two  swollen  areas  near  its  base.  The  scutellum,  or  single 
cotyledon,  is  traversed  by  a  vascular  system.  The  hypo- 
cotyl  is  just  beneath  the  plumule,  being  terminated  at  its 
base  by  the  primary  root. 

Color. — Purple,  blue,  black,  and  red  grains  owe  their  color 
largely  to  a  pigment  located  in  the  sap  of  aleurone  cells.  In 
some  grains,  there  is  a  red  sap  in  the  pericarp.  There  is  an 
absence  of  pericarp,  aleurone  and  endosperm  colors  in  white 
corn.  In  yellow  maize,  the  coloring  matter  occurs  both  in 
the  aleurone  layer  and  in  the  endosperm. 

Com  Starch  Distinguished  from  the  Other  Common 
Starches. — The  following  key,  adapted  from  Winton's 
Microscopy  of  Vegetable  Foods,  gives  the  characteristic 
microscopic  differences  between  the  common  commercial 
starches. 

All  or  most  of  the  grains  rounded,  not  from  aggregates. 

Grains  rounded,  with  central  hilum;  small  grains  globular  jor  angular, 
Wheat. 

Grains  large,  of  various  shapes,  with  excentric  hilum,  Potato. 
Grains  polygonal  or  rounded,  with  one  or  more  facets,  mostly  from  aggregates. 

Grains  very  small,  sharply  angular,  "i?tce. 

Grains  large,  polygonal  or  rounded;  hilum  with  clefts.  Maize. 

Germination  of  Com. — The  germination  of  corn  may  be 
judged  from  the  following  data:  Sachs  says:  optimum  9i°F., 


178  BOTANY  OF  CROP  PLANTS 

maximum  ii4.8°F.,  and  minimum  4i°F.  Sturtevant  further 
shows  that  corn  germinates  in  from  ten  to  twenty  days  at 
a  temperature  of  43.7°F.,  while  at  from  48.6°F.,  to  58.5°F., 
it  germinates  in  from  five  to  ten  days.  In  germination,  the 
primary  root  appears  first,  at  the  tip  of  grain;  soon  the  plu- 
mule breaks  through  the  pericarp  at  about  the  middle  of  the 
grain.  The  young  germinating  grain  consists  of  a  primary 
root  projecting  at  the  peduncle  end,  and  the  plumule  emerg- 
ing through  a  slit  in  the  pericarp  at  about  the  middle  of  the 
grain,  and  pointing  in  the  opposite  direction.  On  the  sides 
of  the  primary  root,  two  secondary  ones  soon  appear,  making 
a  total  of  three  roots  in  the  primary  root  system. 

In  the  seedling,  there  is,  as  in  other  cereals,  a  more  or 
less  elongated  axis  between  the  base  of  the  coleoptile  and 
the  grain.  This  has  been  named  the  mesocotyl  by  some  mor- 
phologists.  Collins  described  seedlings  of  maize  grown  by 
the  Indian  tribes  of  the  southwestern  United  States,  that 
may  develop,  under  conditions  of  deep  planting,  a  mesocotyl 
up  to  36  centimeters  in  length. 

Classification. — The  many  different  varieties  of  cultivated 
corn  are  all  included  under  the  one  name,  Zea  mays  L. 
Sturtevant  has  divided  this  species  up  into  "species  groups" 
(subspecies),  the  most  important  of  which  are  the  following:* 

1.  Zea  tunicata,  pod  corn. 

2.  Zea  everta,  pop  corn. 

3.  Zea  indurata,  flint  corn. 

4.  Zea  indentata,  dent  corn. 

5.  Zea  amylacea,  soft  corn. 

6.  Zea  saccharata,  sweet  corn. 

7.  Zea  amylea-saccharata,  starchy  sweet  corn. 

*The  specific  name  "mays"  is  omitted,  for  convenience,  from  the 
following. 


ZEA  179 

Gerncrt  describes  a  type  of  corn  with  branching  ears  and 
highly  branching  tassels,  which  he  considers  as  a  distinct 
subspecies  and  for  which  he  suggests  the  name  Zea  mays 
ramosa.  Collins  describes  a  new  type  of  Indian  corn  from 
China.  This  has  erect  leaf  blades,  some  upper  leaves  ar- 
ranged in  a  monostichous  manner,  silks  developing  inside  the 
leaf  sheath,  and  grains  with  a  peculiar  waxy  endosperm.     Zea 


Fic.   66.— The  six  principal  lypos  of  corn.      Fr(.in  k-U  to  rik'lit.  P 
pop  corn,  flint  corn,  dent  corn,  soft  c(5rn,  and  sweet  corn.      {After  Montgom- 
ery.) 

canina  Watson,  the  Mai/  de  Coyote,  is  a  branching  plant 
producing  many  small  ears  (2  to  4  inches  long)  on  lateral 
branches.  It  has  been  produced  artificially  by  cros.sing  a 
common  maize  and  teosinte.  It  is  said  to  grow  wild  in 
Mexico  at  the  present  time.  Zea  mays  japonica  is  an  orna- 
mental sort  with  small,  tlinty  grains.  Zea  mays  hirla  is  a 
hairy,  South  x\merican  corn.  Zea  mays  ciiragiia  is  a  forni 
with  serrate  leaves. 


l8o  BOTANY  OF  CROP  PLANTS 

The  distinguishing  characteristics  of  the  seven  groups  above 
are  shown  in  the  following  key: 

Key  to  "Species  Groups"  of  Corn 

Each   kernel    enclosed    in    husks  (glumes,  lemma,  palct);    the  ear  is  also 
enclosed  in  husks;  a  rare  form,  considered  by  some  to  be  the  primitive 
type,  Zca  litnicata  (pod  corn). 
Each  kernel  naked,  not  enclosed  in  pod  or  husk: 

Grains  with  popping  properties;  popping  is  due  to  the  turning  inside  out  of 
the  kernel  through  the  explosion  of   the  contained  moisture  when  heat 
is  applied;  pericarp  is  thick  and  tough;  excessive  proportion  of  horny 
(corneous)  endosperm;  kernels  and  ears  small,  Zea  everta  (pop  corn). 
Grains  without  popping  properties 

No  corneous   endosperm,  hence  grains  are-soft;  shaped  like  flint  corn; 
no  indentation;  the  mummy  corns  of  Peru,   Mexico,   and  southern 
United   States   probably  belong   to    this   group,   Zea  amylacea  (soft 
corn). 
Corneous  endosperm  present. 
Grains  more  or  less  wrinkled  or  shrivelled;   kernels  horny  and  trans- 
lucent in  appearance. 
Grains  horny  throughout,  Zca  saccharala  (sweet  corn). 
Grains  with    upper    half    horny  and    translucent,  the    lower   half 
starchy,  Zca  amylca-saccharala  (starchy  sweet  corn). 
Grains  not  wTinkled,  smooth. 
Starchy  endosperm  extending  to  top  of  kernel;  corneous  endosperm 
at  sides;  shrinkage  of  starchy  endosperm  at  top  of  grain  causes  a 
drawing  in  of  pericarp  and  hence  the  characterist  c  dent  formed 
(Fig.  64),  Zca  indcnlata  (dent  corn). 
Starchy  endosperm   enclosed   by  the  corneous   endosperm;  hence 
there  is  no  shrinkage  of   top  of  grain  and  no  dent  formed  (Fig. 
64),  Zca  iudiirala  (flint  corn). 

Zea  amylea-saccharata  (starchy  sweet  corn)  is  a  group  of 
only  botanical  interest.  Some  seed  of  this  was  found  in  the 
San  Padro  Indian  collection  by  Dr.  Palmer  and  sent  to 
Sturtevant  in  1886.  This  seed  was  planted  at  Geneva, 
New  York,  but  the  crop  failed  and  the  seed  was  lost. 

In  Zea  saccharala,  the  power  to  develop  starch  grains  to 
maturitv  has  been  lost.     The  starch  that  is  formed  remains 


i8i 


small,  angular,  and  docs  not  have  the  appearance  of  the 
typical  corn  starch  granule.     Sweet  corns  may  be  regarded 


Fig.   67. — Tcubiulc   ^.l:;uchlacna  me.xicanaj.      {AJ'ti-r  Collins  ami   Knnpton  in 
Journal  of  Ilercdily.) 

as  dent,  tlint,  and  [)op  corns  that  have   lost  the  power  to 
mature  starch  normally. 

Origin  of  Maize. — Although  maize  or  Indian  corn  has  been 


l82  BOTANY    OF   CROP    PLANTS 

in  cultivation  since  prehistoric  times,  it  is  unknown  in  the 
wild  state.  It  is  generally  agreed,  hawever,  that  it  is  dis- 
tinctly of  American  origin.  The  nearest  known  wild  relative 
of  maize  is  a  Mexican  grass,  leosinle  {EiicJilcena  mcxicana), 
with  which  it  is  known  to  hybridize  (Fig.  67). 

Harshberger  is  inclined  to  believe  "that  Indian  corn  is  the 
result  of  a  cross  between  teosinte  and  a  race  or  variety  of  the 
plant  produced  by  successive  cultivation  of  the  wild  plant 
until  its  characters  as  a  variety  or  a  race  have  become  fixed." 
Collins  produces  evidence  to  show  that  maize  originated  as  a 
hybrid  between  teosinte  and  as  unknown  grass  belonging  to 
the  tribe  Andropogonete.  He  believes  this  grass  to  be  much 
like  the  earless  varieties  of  pod  corn  {Zea  tunicata).  Mont- 
gomery suggests  that  teosinte  and  corn  had  a  common  ances- 
tor, which  was  a  "large,  much-branched  grass,  each  branch 
being  terminated  by  a  tassel-like  structure,  bearing  herma- 
phrodite flowers."  His  views  coincide  with  those  of  East 
and  Hayes  (see  page  164). 

Environmental  Relations. — Corn  is  a  native  of  semi-trop- 
ical America.  Its  range  of  distribution  has  been  extended 
widely  through  culture.  A  number  of  varieties  will  mature 
grain  as  far  north  as  southern  Canada,  and  as  a  green  fodder 
it  is  raised  in  still  colder  regions,  where  the  season  is  too  short 
to  mature  the  grain. 

Flint  varieties  are  now  grown  quite  abundantly  through- 
out northern  Wisconsin;  they  are  better  adapted  to  cool 
climates  than  dent  corn.  In  general,  corn  is  not  a  big  crop 
north  of  the  summer  isotherm  of  69°F.  The  principal  corn 
belt  of  the  United  States  is  a  strip  running  from  eastern 
Nebraska  to  western  Ohio,  the  northern  limit  ])cing  southern 
Wisconsin  and  Minnesota.  This  is  a  region  with  warm  sum- 
mer days  and  nights.  The  chief  limiting  factor  to  corn  grow- 
ing in  the  northern  tier  of  States  is  cool  nights. 


ZEA  183 

Reference  to  page  117  shows  that  the  water  requirement 
of  corn  stands  between  that  of  sorghum  and  wheat.  There 
is  a  significant  difference  in  the  water  requirement  of  the 
varieties  of  corn,  indicating  that  some  may  be  more  drought- 
resistant  than  others.  Corn  is  being  raised  with  profit  on 
the  dry  lands  of  the  West. 

There  is  a  close  correlation  between  the  yield  of  corn  and 
the  rainfall  for  June  and  July.  The  critical  month  is  July. 
Smith  says  that  the  most  critical  ten-day  period  for  corn,  in 
Ohio,  is  from  August  i  to  10,  the  period  following  blossoming, 
when  the  weather  must  be  wet  and  moderately  cool. 

In  the  corn  districts  west  of  the  95th  meridian,  hot  winds 
sometimes  prove  fatal  to  corn.  These  winds  are  particularly 
harmful  during  the  critical  periods  of  "tasseling"  and 
"silking." 

Corn  thrives  best  in  a  well-drained,  medium  loam  soil,  such 
as  is  found  in  the  river  bottoms  of  the  Mississippi  Valley.  It 
will  grow  on  soils  so  rich  in  nitrogen  as  to  cause  the  lodging 
of  the  small  grains. 

Uses  of  Com. — No  other  cereal  is  put  to  such  a  variety  of 
uses  as  is  corn.  •  Some  economical  use  has  been  found  for 
nearly  every  part  of  the  plant.  There  are  numerous  manu- 
factured corn  products  and  by-products.  Corn  meal,  both 
yellow  and  white,  is  one  of  the  chief  forms  in  which  the  grain 
is  used  as  a  food  for  man.  Whole  meal  includes  the  embryo, 
endosperm  and  hull,  while  new  process  meal  has  the  embryo 
and  hull  removed.  Other  forms  in  which  corn  as  a  human 
food  is  used  are:  hominy,  green  corn,  canned  corn,  corn  oil, 
corn  flakes,  pop  corn,  starch,  and  glucose.  The  sweet  corn 
canning  industry  is  a  large  one.  Corn  starch  from  which 
the  protein  and  mineral  matter  have  been  removed  by  treat- 
ment with  dilute  alkaline  solutions  gives  a  flour  which  is  used 
largely  in  the  preparation  of  puddings,  blanc  manges,  etc. 


184  BOTANY  or  CROP  PLANTS 

Corn  oil  is  obtained  from  the  embryo.  When  freshly 
prepared,  it  is  pale  yellow  in  color.  It  is  employed  in  the 
manufacture  of  soap,  and  paints,  and  when  mixed  with  lin- 
seed oil,  it  has  some  value  as  a  grinding  oil.  Corn  oil  is  also 
sometimes  vulcanized  into  a  cheap  grade  of  rubber. 

Corn  Starch. — About  50,000,000  bushels  of  corn  are  used 
annually  in  the  United  States  in  the  manufacture  of  com- 
mercial starches,  and  products  derived  from  them.  In  the 
manufacture  of  corn  starch,  the  corn  is  steeped  from  two  to 
four  days  in  warm  water  containing  about  0.2  per  cent,  of 
sulphurous  acid.  Steeping  is  instituted  in  large  wooden  vats 
holding  about  2,000  bushels  of  corn.  When  the  grains  are 
softened  sufficiently,  they  are  lead  through  a  Fuss  mill  which 
thoroughly  breaks  up  the  grain.  The  embryos  are  separated 
from  the  rest  of  the  grain  material,  and  removed  to  another 
receptacle.  The  disintegrated  grains  are  freed  from  the 
embryos,  mixed  with  water,  more  finely  ground  and  then 
shaken  through  bolting-cloth  sieves.  Starch  and  gluten  pass 
through  the  sieves,  while  the  courser  materials,  such  as  frag- 
ments of  the  pericarp,  are  caught  by  the  sieve.  The  liquor 
containing  starch  and  gluten  is  passed  over  tables,  very 
slightly  inclined,  and  as  the  liquid  slowly  flows  down  these 
tables,  the  starch  granules  settle,  while  the  lighter  particles 
of  gluten  are  carried  off  the  lower  end.  The  starch  is  re- 
moved from  the  tables,  washed,  and  kiln-dried. 

Glucose. — The  commercial  "glucose"  is  a  thick  syrup — a 
product  of  the  partial  hydrolysis  of  starch.  The  manufac- 
ture of  corn  starch  has  been  described.  The  "green 
starch"  from  the  tables  is  made  into  a  thick  cream  by  mix- 
ing with  water.  This  is  then  passed  to  converters  where 
the  starch  is  treated  with  hydrochloric  acid  to  bring,  about 
its  partial  hydrolysis.  The  converted  liquor  is  blown  out 
of  the  converters  into  the  neutralizer,  where  it  is  treated 


ZEA  185 

with  a  dilute  solution  of  sodium  carbonate,  which  neutralizes 
the  acid,  and  precipitates  the  dissolved  iron,  and  coagulates 
the  colloidal  albuminoids.  The  neutral  liquor  is  then  filtered, 
first  in  bag  filters,  and  then  in  bone-char  filters.  From  the 
first  bone-char  filters,  there  issues  a  light  liquor.  This  is 
evaporated  to  increase  its  concentration,  and  passed  on  as 
heavy  liquor  to  the  bone-char  filter  again.  The  liquor  that 
results  from  this  second  filtering  is  boiled  down  in  vacuum 
pans,  whence  it  comes  as  the  finished  glucose. 

Pure  glucose  syrup  has  Httle  flavor,  and  but  half  the  sweet- 
ness of  cane  syrup.  Maize  syrup  is  mixed  with  varying 
quantities  of  cane  syrup  and  sold  as  a  substitute  for  golden 
syrup  and  molasses.  It  is  the  basis  of  many  manufactured 
jellies  and  preserved  fruits. 

Grape  Sugar. — This  is  a  crude  sugar  made  from  starch, 
in  a  manner  very  similar  to  that  employed  in  the  manufac- 
ture of  glucose.  However,  hydrolysis  is  more  complete,  the 
process  of  conversion  being  carried  to  the  point  that  no  dex- 
trin is  precipitated  when  a  sample  is  placed  in  strong  alcohol. 
Grape  sugar  appears  on  the  market  as  a  hard,  waxy  solid. 
It  finds  considerable  use  in  the  manufacture  of  sparkling 
ales;  and,  also,  as  a  reducing  agent  in  indigo  dyeing,  and  other 
industries. 

Artificial  Gums. — These  are  known  as  dextrins  and  British 
gums,  and  are  made  from  starch.  Starch  is  heated  to  a 
temperature  varying  from  170  to  27o°C.  During  this  proc- 
ess, the  starch  may  be  treated  with  dilute  nitric  acid  to  bring 
about  hydrolysis,  although  if  high  temperatures  are  used, 
the  addition  of  acid  is  unnecessary,  as  the  starch  itself  con- 
tains enough  acid  and  water  to  effect  hydrolysis.  Dextrins 
and  British  gums  are  used  on  envelopes  and  postage  stamps, 
and  also  in  many  of  the  textile  industries. 

Stock  Food. — Corn  fodder  includes  the  whole  plant — stalks, 


1 86  BOTANY  OF  CROP  PLANTS 

leaves,  and  ears — and  in  this  form  is  fed  to  stock.  Corn 
stover  is  the  stalks  of  corn  from  which  the  ears  have  been 
husked;  the  stalks  may  be  fed  in  the  bundle  form  or  shredded. 
Fodder  is  an  important  silage  crop.  In  the  form  of  silage, 
it  makes  a  highly  nutritious,  succulent  feed  throughout  the 
winter.  Silage  is  a  forage  prepared  by  fermenting  green, 
fresh,  plants  in  a  specially  constructed  air-tight  receptacle, 
called  a  silo.  The  material  to  be  ensilaged  is  cut  into  fine 
pieces  and  packed  into  the  silo.  Forage  crops  include,  ac- 
cording to  common  usage,  those  plants  which  are  grown 
for  their  vegetative  parts  and  which  are  eaten,  either  in  the 
green  or  dry  state,  by  herbivorous  animals.  Some  plants, 
such  as  sorghums,  are  grown  for  their  grain  and  also  for 
their  herbage,  that  is,  they  are  both  a  cereal  and  a  forage 
crop.  Corn  Is  also  both  a  cereal  and  a  forage  crop.  The 
grass  family  (Gramineae)  and  the  pea  family  (Leguminosae) 
furnish  the  great  majority  of  forage  plants.  Corn  grain  and 
corn  bran  are  important  stock  foods. 

Other  Corn  Products. — The  pith  from  the  stalks  is  made 
into  explosives  and  also  employed  as  a  packing  material 
where  extreme  lightness  of  weight  is  required.  Corn  cobs 
are  still  in  demand  for  pipes.  A  fine  grade  of  charcoal  is 
manufactured  from  corn  cobs.  Paper  is  made  from  the 
stalks,  and  packing  for  mattresses  from  the  husks.  When  oil 
is  pressed  from  the  embryos,  there  is  left  the  corn  cake,  which 
may  be  utilized  as  a  food  for  stock.  Gluten  meal,  a  by- 
product from  starch  factories,  is  also  not  infrequently  fed  to 
stock.  Corn  is  the  most  economical  source  of  starch  for 
alcohol  manufacture  in  the  United  States.  One  ton  of  com 
gives  about  90  gallons  of  94  per  cent,  alcohol. 

Production  of  Com.^ — In  1914,  the  United  States  produced 
2,672,804,000  bushels  of  corn,  which  was  over  70  per  cent, 
of  total  production  for  the  world.     The    country  ranking 


ZEA  187 

second  in  its  corn  output  was  Argentine  with  338,235,000 
bushels.  The  ten  leading  States  in  the  order  of  their  pro- 
duction of  corn  in  191 5  were  Illinois,  Iowa,  Nebraska,  Mis- 
souri, Indiana,  Texas,  Kansas,  Ohio,  Oklahoma,  and  Ken- 
tucky. The  total  acreage  in  corn  in  the  United  States 
that  year  was  108,321,000  and  the  total  farm  value  of  the 
1 91 5  corn  crop,  on  the  basis  of  the  price  of  corn  December  i, 
was  $1,755,859,000. 


Fig.  68. — Percentage  of  the  world's  supply  of  corn  produced  in  the  various 
countries  in  1914. 


References 

BoHUTiNSKY,  GusTAv:    EntwicklungsabweichuDgen  beim  Mais.    Ber.  Deut. 

Bot.  Gesell.,  32:  179-188,  1914. 
Bowman,  M.  L.,  and  Crossley,  B.  W.:  Corn:  Growing,  Judging,  Breeding, 

Feeding,  Marketing.    Waterloo,  Iowa,  191 1. 
BxiRTT,    Davy   J.:  Botanical   Characters   of    the  Maize  Plant.     Transvaal 

Agr.  Jour.,  7:  34-8-395,  iQOQ- 
Incomplete  Dichogamy  in  Zea  Mays.     Jour.  Bot.  (London),  47:180-182, 

1909. 
Maize,  Its  History,  Cultivation,  Handling,  and  Uses.    Longmans,  Green  & 

Co.,  1914. 
Collins,  G.  N.:  A  New  Type  of  Indian  Corn  from  China.     U.  S.  Dept.  Agr. 

Bur.  Plant  Ind.  Bui.  161:  1-25,  1909. 


ZEA  189 

Apogamy  in  the  Maize  Plant.     U.  S.  Nat.  Mus.  Contrib.  Nat.  Herbarium, 

12:453-455,  1909. 
The  Origin  of  Maize.     Jour.   Washington  Acad.  ,Sci.,  2:  520-530,1  912. 
A  Variety  of  Maize  with  Silks  Maturing  Before  the  Tassels.     U.  S.  Dept. 

Agr.  Bur.  Plant  Ind.  Cir.  107:  i-ii,  1913. 
A  Drought-resisting  Adaptation  in  Seedlings  of  Hopi  Maize.     U.  S.  Dept. 
Agr.  Jour.  Agr.  Research,  j :  293-302,  1914. 
CoRRENS,  C:  Untersuchungen  uber  die  Xenien  bei  Zea  mays.     Ber.  Deut. 

Bot.  Gesell.,  17:410-417,  1899. 
Crozier,  a.  a.:  Silk-seeking  Pollen.     Bot.  Gaz.,  13:242,  1888. 
East,  E.  M.:  Inheritance  of  Color  in  the  Aleurone  Cells  of  Maize.     Amer. 
Nat.,  46:363-365,  191 2. 
A  Chronicle  of  the  Tribe  of  Corn.     Pop.  Sci.  Mo.,  82:225-236,  1913. 
East,  E.  M.,  and  Haves,  H   K.:  Inheritance  in  Maize.     Conn.  Agr.  Exp. 

Sta.  Bull.  167:1-142,  1911. 
Fisher,  M.  L.:  Report  of  Work  in  Corn  Pollination,  I.     Proc.  Ind.  Acad. 
Sci.,  1908. 
Report  of  Work  in  Corn  Pollination,  II.     Proc.  Ind.  Acad.  Sci.,  1910. 
Report  of  Work  in  Corn  Pollination,  III.     Proc.  Ind.  Acad.  Sci.,  191 1. 
Gager,  C.  S.:  An  Occurrence  of  Glands   in   the   Embryo   of   Zea  Mays. 

Bull.  Torrey  Bot.  Club,  34:  125-137,  1907. 
Gernert,  W.  B.:    Methods  in    the  Artificial  Pollination  of  Corn.     Am. 
Breeders'  Assn.,  7:  353-367,  1911. 
A  New  Subspecies  of  Zea  Mays.     Am.  Nat.,  47:  616-622,  1912. 
GuiGNARD,  L.:  La   double  fecondation   dans  le  mais.     Jour.  Bot.  (Paris), 

15: 37-50,  1901. 
Harshberger,  J.  W.:  Maize:  A  Botanical  and  Economic  Study.     Contrib. 
Bot,  Lab.  Univ.  Pa.,  i :  75-202,  1893. 
Fertile  Crosses  of  Teosinite  and  Maize.     Gard.  and  Forest,  9:  522-523, 

1896. 
A  Study  of  the  Fertile  Hybrids  Produced  by  Crossing  Teosinte  and  Maize. 
Contrib.  Bot.  Lab.  Pa.,  2,  190T. 
Hopkins,  C.  G.,  Smith,  L.  H.,  and  East,  E.  M.:  The  Structure  of  the  Corn 
Kernel  and  the  Composition  of  its  Different  Parts.     111.  Agr.  Exp.  Sta. 
Bull.  87:  77-112,  1903. 
Hus,  H.,  and  Murdock,  A.  W.:  Inheritance  of  Fasciation  in  Zea  Mays. 

Plant  World,  14:  88-96,  1911. 
Kellerman,  W.  a.,  and  Swingle,  W.  T.  :  Preliminary  Study  of  the  Recep- 
tivity of   Corn   Silk.     2d  Ann.  Rept.  Kans.  Agr.  Exp.  Sta.,  353-355, 
1890. 
Bibliography  of  Cross-fertilization  of  Varieties  of  Corn.     2d  Ann.  Rept. 
Kans.  Agr.  Exp.  Sta.,  346-353,  1890. 


igo  BOTANY  OF  CROP  PLANTS 

Experiments  in  Cross-fertilization  of  Corn,     ad  Ann.  Rapt.  Kans.  Agr. 

Exp.  Sta.,  288-334,  1890. 
Experiments  in  Crossing  Varieties  of  Corn.     2d  Ann.  Rept.  Kans.  Agr. 
Exp.  Sta.,  2:  288-334,  1890. 
Kempton,  James  H.:  Floral  Abnormalities  in  Maize.     U.  S.  Dept.  Agr. 

Bur.  Plant  Ind.  Bull.  278:  1-16,  1913. 
Montgomery,  E.  G.:  What  is  an  Ear  of  Corn?     Pop.  Sci.  Mo.,  68:  55-62, 
1906. 
Perfect  Flowers  in  Maize.     Pop.  Sci.  Mo.,  79:  346-349,  191 1. 
The  Corn  Crops.     The  Macmillan  Co.,  New  York,  1913. 
Peirson,  Henry:  Abnormal  Development  in  Maize.     Jour.  Bot.  (London), 

49:347-348,  1911- 
PoiNDEXTER,  C.  C:  The  Development  of  the  Spikelet  and  Grain  of  Corn. 

Ohio  Nat.,  6,  1903. 
Sargent,  Ethel,  and  Robertson,  Agnes:  The  Anatomy  of  the  Scutellum 

in  Zea  Mays.     Ann.  Bot.,  19:  1 15-123,  1905. 
Shoesmith,  V.  M.:  The  Study  of  Corn.     Kans.  Agr.  Exp.  Sta.  Bull.  139: 
223-249,  1906. 
The  Study  of  Corn.     Orange  Judd  Co.,  1910. 
Stewart,  Alban:  The  Pistillate  Spikelet  in  Zea  Mays.     Science,  n.s.  42: 

694,  1915. 
STtTRTEVANT,  E.  L.:  Notcs  on  Maize.     Torrey  Bot.  Bull.  21:  319-343)  1894. 
Varieties  of  Corn.     U.  S.  Dept.  Agr.  Office  Expt.  Stats.  Bull.  5/:  1-103, 
1899. 
Weatherwax,   Paul:  Morphology  of   the   Flowers   of   Zea  Mays.     Bull, 

Torrey  Bot.  Club,  43:  127-144,  1916. 
Webber,  H.  J.:  Xenia,  or  the  Immediate  Effect  of  Pollen  in  Maize.     U.  S. 
Dept.  Agr.  Div.  Veg.  Path,  and  Veg.  Phys.,  22:  1-44,  19°°- 


CHAPTER  XV 

ANDROPOGON  SORGHUM  (Sorghums^) 

Habit  of  Plant,  and  Roots. — All  sorghums  are  annual. 
The  root  system  is  well  developed.  The  roots  are  generally 
finer  and  more  fibrous  than  those  of  maize.  The  root  crowns 
and  laterals  show  a  vigorous  growth.  Sorghum  is  more  of  a 
surface  feeder  than  corn,  its  roots  being  chiefly  in  the  first 
1 8  inches.     The  roots  of  all  sorghums  are  tough  and  wiry. 

Stems  and  Leaves. — The  culms  vary  in  height  from  3  to 
15  feet.  .They  are  solid;  the  internodes  and  leaf  sheaths  are 
about  equal  in  length.  Sorghums  produce  both  ''suckers" 
and  side  branches  from  buds  placed  in  the  axils  of  the  leaves. 
As  many  as  10  or  15  suckers  may  be  produced  from  one 
plant;  they  differ  from  the  main  stalk  in  that  they  are  less 
tall,  and  mature  later.  Side  branches  do  not  appear  until 
the  main  stem  is  headed  out.  The  heads  on  these  branches 
are  smaller  and  less  productive  than  those  on  the  main  stalk, 
and  they  mature  much  later. 

The  leaves  are  very  similar  to  those  of  corn. 

Inflorescence. — This  is  a  panicle,  which,  with  a  few  excep- 
tions {e.g.,  broom  corn),  is  rather  compact.  It  is  called  the 
"head."  These  heads  may  vary  (Fig.  73)  a  great  deal  in 
shape  and  color.  The  axis  of  the  inflorescence  is  rather 
angular.  The  side  branches  are  in  apparent  whorls,  one 
above  the  other.  The  spikelets  usually  occur  in  pairs  (Fig. 
70),  although  toward  the  tip  of  the  inflorescence  they  may 
occur  in  threes. 

^  The  term  "sorghum"  includes  all  the  groups  known  in  the  United  States 
as  milo,  kowliang,  shallu,  durra,  broom  corn,  and  kafir. 
191 


192 


BOTANY   OF   CROP   PLANTS 


Spikelets  and  Flowers.^It  was  stated  that  the  spikelets 
usually  occur  in  pairs.  One  is  sessile,  the  other  pedicelled. 
The  sessile  one  is  broad,  thick,  and  fertile;  the  pedicelled 
narrow,  long,  and  staminate.  Whenever  three  spikelets  are 
in  a  group,  one  is  sessile  and  perfect,  and  two  are  pedicelled 
and  staminate;  sometimes  one  of  the  two  stalked  spikelets 
may  be  perfect. 


horn\/  enSosperm 


Zndglui 

\ 


embr\}(/\J  " 
j/yfe  branch^ 


■sienle 


Fig.  70. — Sorghum  (Andropogon  sorghum).     A,  pair  of  spikelets;  B,  grain  in 
section;  C,  grain,  external.      X  5- 


Fertile  Spikelet  (Fig.  71). — The  sessile  spikelet  has  thick, 
leathery  glumes  of  about  equal  length.  The  outer  one  par- 
tially wraps  about  the  inner.  The  latter  is  narrower  and 
more  gradually  tapering  at  the  tip.  Within  the  two  glumes 
of  this  sessile  spikelet,  are  two  flowers;  the  lower  sterile,  the 
upper  with  both  stamens  and  pistil.  The  so-called  "third 
glume"  of  some  descriptions  is  the  lemma  of  the  lower,  sterile 
flower.     Moreover,  it  is  the  only  remnant  of  this  flower.     It 


ANDROPOGON   SORGHUM 


193 


encloses  the  parts  of  the  fertile  flower.  The  lemma  of  the 
fertile  flower  is  broad,  hairy,  and  two-cleft  at  the  tip;  there 
arises  in  the  cleft,  as  a  rule,  a  long  awn  which  projects  from 
the  spikelet.  The  awn  may  be  very  short  or  only  represented 
by  a  bristle.     The  palet  is  frequently  absent;  when  pres- 


lemma  of  sterile  jlower- 


aniher 


Fig.  71. 


—ovar\j 
lemma  of  fertile  jlower- 

-Spikelet  of  sorghum  (Andropogon  sorghum)  dissected. 
X  10,  all  others  X  5. 


Lodicule 


ent,  it  is  small  and  thin.  There  are  two  lodicules,  which  are 
much  broader  than  long,  truncate,  fleshy,  and  usually 
thickly  hairy.  Three  stamens  are  present.  The  sessile, 
ovate  ovary  does  not  bear  a  tuft  of  hairs  at  the  tip,  such  as  is 
found  in  wheat,  oats,  rye,  and  barley.  The  two  styles  are 
thread-like  and  bare  for  the  lower  two-thirds  of  their  length, 
and  then  spread  out  into  bushy  stigmas. 
13 


194  BOTANY  OF  CROP  PLANTS 

Staminate  Spikelet. — The  stalked  spikelet  is  narrower,  and 
more  pointed  than  the  fertile  one.  It  is  two-flowered.  It  is 
subtended  by  two  leathery  glumes.  Immediately  within 
this  pair  is  the  lemma  of  the  sterile  flower  of  the  spikelet. 
Then  comes  the  lemma  of  the  staminate  flower;  it  may  be 
short-awned  or  awnless;  the  palet  of  this  flower  is'^absent. 
The  lodicules  and  stamens  resemble  those  of  the  fertile  spike- 
let.    There  is  no  pistil. 

Opening  of  Flowers  and  Pollination. — Flowers  do  not  be- 
gin to  open  on  the  inflorescence  until  the  latter  is  entirely  out 
of  the  leaf  sheath.  The  first  flowers  to  open  are  those  near 
the  tip  of  the  head.  Blooming  proceeds  from  the  tip  down- 
ward. As  a  rule,  flowers  at  the  tip  of  an  inflorescence  have 
shed  their  pollen,  and  closed,  when  the  lower  flowers  of  the 
head  are  just  beginning  to  bloom.  Flowers  on  branches  be- 
longing to  one  whorl  are  usually  in  about  the  same  stage  of 
blooming.  In  nearly  all  cases,  the  sessile  spikelet  of  a  pair  is 
the  first  to  open.  The  stalked  spikelets  may  sometimes  fail  to 
protrude  their  stamens.  Most  of  the  flowers  open  in  the  early 
morning;  there  is  but  very  slight  amount  of  blooming  during 
the  day.  The  stigmas  may  protrude  to  a  shght  extent  first. 
(Fig.  7  2) .  They  are  followed  by  the  anthers.  When  the  flower 
starts  to  open,  the  whole  process  takes  place  within  from  ten 
to  fifteen  minutes.  The  spreading  of  the  glumes,  and  the 
emergence  of  anthers  and  styles  may  be  so  rapid  in  some^in- 
stances  as  to  be  seen  with  the  hand  lens.  The  stamens  ex- 
tend their  full  length,  as  a  rule,  and  the  anthers  swing  on  long 
filaments.  In  some  cases,  however,  the  anthers  never  fully 
project  from  between  the  glumes,  but  shed  their  pollen,  and 
dry  up,  half  or  one-fourth  caught  by  the  glumes.  When  the 
anthers  are  partly  out,  the  stigmas  are  fully  protruded.  No 
sooner  are  the  anthers  visible  than  they  begin  to  dehisce  by 
two  narrow  slits  at  the  tip  only.     The  stigmas  and  pollen- 


ANBROPOGON   SORGHUM 


195 


shedding  anthers  may  be  in  contact  at  time  of  opening,  and 
since  the  stigma  is  receptive  at  this  time,  some  self-poHination 
must  take  place.     Pollination  between  flowers  of  the  same 


Fig.  72. — Four  stages  in  the  opening  of  the  spikelet  of  sorghum  (Andropogon 
sorghum).      X  5- 

plant  is  very  common.  The  upper  flowers  are  shedding  pol- 
len in  abundance,  as  the  receptive  stigmas  of  lower  flowers  are 
opening.     And,  in  the  light  breeze  of  the  morning,  the  head  is 


196  BOTANY   OF   CROP  PLANTS 

moved  enough  to  shake  pollen  out.  Cross-polHnation  is  also 
very  common.  Individual  flowers  do  not,  as  a  rule,  remain 
open  longer  than  the  evening  of  the  day  they  open.  The 
brown  and  withered  stamens  and  stigmas  commonly  protrude 
from  between  the  closed  glumes. 

The  different  types  of  sorghum  cross  readily. 

Fruit. — The  mature  grain  may  be  entirely  or  in  part  en- 
closed by  the  "glumes."  It  is  oval,  a  Httle  longer  than  broad, 
smooth,  and  tipped  with  the  remains  of  two  style  branches. 
The  position  of  the  embryo  is  seen  at  the  base  of  the  grain  on 
one  of  the  flat  surfaces.  The  point  of  attachment — an  oval, 
brown  area— is  found  at  the  base  of  the  grain  on  the  other 
flat  surface. 

The  seed  is  flattened  in  the  durras,  pyriform  in  some  of  the 
sorgos,  and  globular  in  kafir,  kowliang,  and  shallu. 

In  some  types  of  sorghum,  the  pericarp  bears  starch.  The 
aleurone  layer  consists  of  one  row  of  small  cells.  The  starchy 
endosperm  is  mealy  within  and  more  or  less  horny  without. 

Varieties. — The  sorghums  are  divided  into  two  main  di- 
visions: (i)  saccharine  or  sweet  sorghums,  and  (2)  non-sac- 
charine sorghums.  Saccharine  sorghums  are  tall,  leafy,  and 
have  an  abundance  of  sweet  juice,  and  a  light  crop  of  seed. 
The  chief  varieties  are  Amber,  Orange,  and  Sumac.  Non- 
saccharine  sorghums  are  more  stocky,  as  a  rule,  contain  less 
juice,  and  have  a  heavy  crop  of  seed.  Non-saccharine 
sorghums  are  divided  into  three  groups;  (i)  kafir  group,  in- 
cluding those  with  erect,  long  cylindrical  heads  full  of 
obovate  seeds  (kafirs,  white  milo,  etc.);  (2)  durra  group, 
including  those  with  thick,  compact,  ovate,  pendant  inflo- 
rescences, and  large,  flattened  seeds  (yellow  milo,  durra, 
feterita) ;  and  (3)  hroom  corn  group,  in  which  the  heads  are 
loose  and  spreading.  Frequently  the  heads  are  on  recurved 
stems,  called  "goose  necks." 


ANDROPOGON    SORGHUM  T97 

Kky  to  the  Principal  Groups  of  Sorguumi 

['ilh  juicy. 
Juice  abundant  and  very  sweet. 

Internodes  elongated;  sheaths  scarcely  overlapping;  leaves  12  to  15  (ex- 
cept in  .\mber  varieties);  spikelets  elliptic-oval  to  obovate,  2.5  to  3.5 
millimeters  wide;  seeds  reddish  brown,  Sorgo. 
Juice  scanty,  slightly  sweet  to  subacid. 

Internodes  short;  sheaths  strongly  overlapping;  leaves  12  to  15;  peduncles 
erect;  panicles  cylindrical;  spikelets  obovate,  3  to  4  millimeters  wide: 
lemmas  awnless,  Kafir. 
Internodes  medium;  sheaths  scarcely  overlapping;  leaves  8  to  11;  ped- 
uncles mostly  inclined,  often  recurved;  panicles  ovate;  spikelets  broad- 
ly obovate,  4.5  to  6  millimeters  wide;  lemmas  awned,  Milo. 
Pith  dry. 

Panicle  lax,  2.5  to  7  decimeters  long;  peduncles  erect;  spikelets  elliptic- 
oval  or  obovate,  2.5  to  3.5  millimeters  wide;  lemmas  awned. 
Panicle  4  to  7  decimeters  long;  rachis  less   than  one-fifth   as   long  as 
the  panicle. 
Panicle  umbelliform,  the  branches  greatly  elongated,  the  tips  droop- 
ing; seeds  reddish,  included,  Broom  Corn. 
Panicle   2.5  to  4  decimeters  long;  rachis   more  than  two-thirds  as  long 
as  the  panicle. 
Panicle  conical,  the  branches  strongly  drooping;  glumes  at  maturity 

spreading  and  involute;  seeds  white  or  somewhat  buff,  Sliallii. 
Panicle  oval  or  obovate,  the  branches  spreading;  glumes  at  maturity 
apprcssed,  not  involute;  seeds  white,  brown,  or  reddish,  Ko7diaiifi. 
Panicle  compact,  i  to  2.5  decimeters  long;  peduncles  erect  or  recurved; 
rachis  more  than  two-thirds  as  long  as  the  panicle. 
Spikelets  elliptic-oval  or  obovate,  2.5  to  3.5  millimeters  wide;  lemmas 

awned,  Kouiiang. 
Spikelets  broadly  obovate,  4.5  to  6  millimeters  wide. 

Glumes  gray  or  greenish,  not  wrinkled;  densely  puliescent;  lemmas 

awned  or  awnless;  seeds  strongly  llattened,  Diirra. 
Glumes  deep  brown  or  black,  trans\ersely  wrinkled;  thinly  pubescent; 
lemmas  awned;  seeds  slightly  flattened,  Milo. 

Origin  of  Sorghums. — The  wild  form  from  which  our  culti- 
\at(.'tl  sorghums  have  been  derived  is  Andropogon  halcpensis 
(Johnson  grass) .     This  species  is  native  to  tropical  and  sub- 
tropical  parts  of  the  Old  World.     The  view  is  now   quite 
^  Taken  from  Ball. 


1 98 


BOTANY   OF    CROP   PLANTS 


ANDROPOGON   SORGHUM  I99 

generally  adopted  that  the  present-day  cultivated  sorghums 
can  be  divided  into  two  groups,  each  of  which  had  an 
independent  origin  in  Asia  and  Africa  respectively. 

Environmental  Relations. — Sorghums  are  of  tropical 
origin,  and  are  more  at  home  in  regions  with  warm,  sunshiny 
summers.  The  plant  will  undergo  high  temperatures.  It 
is  sensitive  to  low  temperatures,  and  consequently  cannot  be 
planted  as  early  in  the  season  as  the  other  small  cereals. 

The  sorghums  are  either  able  to  resist  or  to  escape  drought. 
For  this  reason  they  have  become  one  of  the  principal  crops 
on  the  non-irrigated  lands  of  the  West.  Their  resistance  to 
drought  is  due  largely  to  their  low  water  requirement,  along 
with  their  ability  to  roll  the  leaves  with  approaching  dry 
periods,  and  thus  reduce  the  water-losing  surface,  and  also 
to  their  ability  to  remain  alive  during  a  period  of  drought  and 
quickly  resume  growth  when  moisture  is  available.  In  this 
last  respect  the  sorghums  differ  from  corn,  for  corn  is  unable 
to  remain  in  a  dormant  state  for  a  very  long  time.  The  sor- 
ghums are  not  as  easily  affected  by  hot  winds  as  corn. 
This  is  an  important  characteristic  adapting  them  to  the 
semi-arid  regions. 

Sorghums  will  grow  on  a  variety  of  soils.  They  are  some- 
what more  resistant  to  alkali  salts  than  the  other  grain  crops. 

Uses  of  Sorghums. — The  saccharine  or  sweet  sorghums 
are  grown  for  syrup  and  for  forage.  The  juice  is  extracted 
from  the  canes.  The  leading  State  in  sorghum-syrup  pro- 
duction is  Tennessee.  The  non-saccharine  sorghums  are 
grown  chiefly  for  their  grain,  but  also  for .  forage.  The  Chi- 
nese and  Manchus  put  the  grain  sorghums  to  a  great  variety 
of  uses.  For  example,  a  fermented'  drink  is  made  from  the 
seed,  the  heads  are  used  for  fuel  and  brooms,  the  leaves  for 
fodder  and  for  mats,  the  stalks  for  the  construction  of  baskets, 
fences,  building  material,  laths,  playthings,  posts,  thatchings, 


200  BOTANY  OF  CROP  PLANTS 

wind  breaks,  and  window  shades,  and  even  the  roots  and 
stubble  are  used  as  fuel.  The  broom-corn  groups  of  sor- 
ghums are  grown  for  their  grain,  and  certain  varieties 
with  long  rachi  are  made  into  brooms.  For  this  purpose 
the  heads  are  used.  Brooms  are  made  from  two  different 
groups  of  broom  corn:  tall-growing  or  Standard,  and  dwarf. 
Fully  two-thirds  of  the  total  broom-corn  crop  of  the 
United  States  is  dwarf  broom  corn.  It  produces  a  fiber 
that  is  finer  than  that  of  the  tall-growing  sort;  and,  too 
the  head  is  not  so  firmly  attached  to  the  upper  node.  This 
latter  character  permits  the  "brush"  (inflorescence)  to  be 
harvested  by  pulling.  After  threshing  the  grain  from  the 
heads,  they  are  cured  in  sheds  or  out  of  doors  in  ricks.  They 
are  then  graded  and  baled,  and  either  stored  or  shipped 
directly  to  the  broom  factory.  The  "straws"  of  a  broom 
are  the  rachises  of  the  sorghum  inflorescence.  Oklahoma, 
Kansas,  and  Texas,  in  the  order  named,  are  the  leading 
broom-corn  States. 

References 

Ball,  CARLEibN  R.:  Saccharine  Sorghums  for  Forage.     U.  S.  Dept.  Agr. 

Farmers'  Bull.  246:  7-18,  1906. 
Three  Much  Misrepresented  Sorghums.     U.  S.  Dept.  Agr.  Bur.  Plant  Ind. 

Cir.  50:  I-I4)  1910. 
The  History  and  Distribution  of  Sorghum.     U.  S.  Dept.  Agr.  Bur.  Plant 

Ind.  Bull.  175:  1-63,  1910. 
Better   Grain-sorghum   Crops.     U.    S.   Dept.   Agr.   Farmers'   Bull.   448: 

1-36,  1911- 
The  Importance  and  Improvement  of  the  Grain  Sorghums.     U.  S.  Dept. 

Agr.  Bur.  Plant  Ind:  Bull.  203:  1-45,  1911. 
The  Grain  Sorghums,  Immigrant  Crops  that  Have  Made  Good.     U.  S. 

Dept.  Agr.  Yearbook,  1913:  221-238. 
Hackel,  E.:  Die  kultivirten    Sorghum — Formen    und   ihre  Abstammung. 

Jahrb.  (Engler),  7:  115-126,  1885. 
Piper,  C.  V.:  The  Prototype  of  the  Cultivated  Sorghums.     Jour.  Am.  Soc. 

Agron.,  7:  109-117,  1915. 


ANDROPOGON    SORGHUM  201 

Hartley,  Charles  P.:  Broom  Corn.     U.  S.   Dept.  Agr.   Farmers'  Bull. 

174:  1-30,  1903. 
RoTHGEB,  B.  E.:  Dwarf  Broom  Corns.     U.  S.  Dept.  Agr.  Farmers'  Bull. 

768:  i-i6,  1916. 
Warburton,   C.   W.:  The  Non  saccharine  Sorghums.     U.   S.   Dept.  Agr. 

Farmers'  Bull.  288:  1-28,  1907. 


CHAPTER  XVI 
ORYZA  SATIVA  (Rice) 

Habit,  Roots,  Stems,  Leaves. — Common  cultivated 
rice  is  an  annual  plant,  which  grows  best  under  swampy 
or  very  moist  conditions.  There  are  upland  varieties  pro- 
duced with  irrigation,  but  the  lowland  type  is  the  sort 
almost  entirely  grown  in  the  United  States.  The  seedHng 
has  one  seed  root.  The  root  system  is  fibrous;  the  first, 
second,  and  third  nodes  give  rise  to  adventitious  roots. 
The  first  whorl  of  permanent  roots  is  close  to  ^^  inch  above 
the  lower  end  of  the  culm.  It  is  more  shallow  in  very  moist 
ground  than  in  dry  soil.  The  plant  tillers  freely,  sending  up 
usually  four  or  five  hollow  stems  to  a  height  of  2  to  6  feet. 
The  leaf  sheaths  are  open,  and  the  blades  are  from  8  to  12 
inches  long  and  %  to  i  inch  wide.  The  ligule  is  long,  acute 
or  obtuse,  and  easily  splits  into  two  parts.  It  is  much  shorter 
and  more  rounded  on  the  upper  leaves  than  on  the  lower. 
The  auricle  is  white  or  green,  cartilaginous  or  membranous, 
and  hairy. 

Inflorescence  and  Spikelet. — The  inflorescence  is  a  pan- 
icle (Fig.  74).  Its  branches  are  either  single  or  in  pairs. 
The  spikelet "  (Fig.  75)  is  compressed  laterally.  It  is  one- 
flowered.  There  are  two  small  scale-like  or  bristle-like 
glumes,  underneath  each  of  which  is  a  very  minute,  rudi- 
mentary glume.  The  lemma  is  compressed,  parchment-like 
and  five-nerved.  The  palet  is  similar  to  the  lemma  in  size 
and  texture,  but  is  only  three-nerved.  Both  may  be  awned 
or  awnless.     The  broadly  oval  lodicules  are  small,  thick,  and 


ORYZA    SATR'A 


203 


fleshy.  Rice  dilTcrs  markedly  from  the  other  common  cereals 
in  having  six  well-developed  and  functioning  stamens.  The 
ovary  is  somewhat  longer  than  broad,  smooth,  and  bears  two 


Fig.    74. — Panicle  of  rice  (Oryza  sativa). 


styles,  and  sometimes  a  short,  rudimentary  third  one.     These 
three  are  sometimes  grown  together  at  the  base. 
Pollination  and  Fertilization.— Rice  is  normally  self-polli- 


?04 


BOTANY   OF    CROP   PLANTS 


nated.     The  flowers  at  the  tip  of  the  inflorescence  are  the  flrst 


to  open. 


--H-'M- lemma 


Flower  opening  continues  throughout  the  clay. 
The  stamens  are  the  first  flower  parts  to 
appear.-  After  they  are  extended  full 
length,  the  lemma  and  palet  open  wider, 
and  the  stigmas  protrude.  Usually  the 
stigmas  draw  back  between  the  palet 
and  lemma  after  pollination,  although 
they  may  remain  outside.  Although 
self-fertilization  is  the  normal  process, 
cross-fertilization  is  not  altogether  pre- 
cluded. 

Grain.^ — The  rice  grain  (caryopsis)  is 
surrounded  by  the  lemma  and  palet,  or 
palet  alone.  These  two  structures  form 
the  "hull."  Rice  enclosed  in  the  hull  is 
known  as  ''paddy."  Rice  from  which 
the  hull  has  been  removed  is  "cleaned 
rice."  The  rice  grain  (Fig.  76)  is 
smooth,  longer  than  broad,  and  elliptical  in  cross-section. 
There  are  two  longitudinal  parallel  ridges  on 
each  of  the  flat  surfaces.  The  grain  of  common 
rice  is  shiny  and  transparent.  This  appearance 
is  due  to  the  glassy  endosperm.  Occasionally 
there  arc  grains  that  appear  dull;  in  such,  the 
endosperm  is  starchy  on  the  outside  and  horny 
within,  (rrains  with  dull  areas  here  and  there 
are  not  uncommon.  An  interesting  rice  is 
Oryza  glulinosa,  the  grains  of  which  always 
appear  dull.  A  cut  surface  of  this  rice  is  de- 
scribed 'as  j)arairin-iike  in  aj)pearance.  The 
starch  grains  behave  c^uite  dilYerently  from  those  of  common 
rice.     They  color  yellow-brown  with  iodine  instead  of  violet. 


Fig.  75. — Spikelet  of  rice 
(Oryza  sativa). 


Fig.  76.— 
Kernel  of  rice 
(Oryza  sativa). 
c.      embryo. 


ORYZA   SATIVA  20S 

When  it  is  cooked,  there  is  formed  a  mass  the  particles  of 
which  stick  closely  together;  the  single  grains  do  not  remain 
separate.  There  are  rices  with  grains  pale  green  in  color, 
reddish-brown,  dark  brown,  and  white  with  red  or  dark 
stripes. 

In  cross-section  of  the  rice  grain,  the  layers  are  very  similar 
to  those  in  wheat.  There  is  the  pericarp  of  several  layers,  the 
testa,  the  nucellus  (perisperm),  and  the  aleurone  layer,  usu- 
ally of  one  row  of  cells.  The  embryo  is  about  one-third 
the  length  of  the  fruit.  During  the  milling  process,  the 
lemma  and  palet,  the  embryo,  pericarp,  testa,  nucellus,  and  in 
many  cases  all  or  a  portion  of  the  aleurone  layer  are  removed. 
This  "scouring  process,"  in  the  case  of  Honduras  and  Japan 
rices,  removes  about  lo  per  cent,  of  the  weight  of  the  grain, 
and  a  considerable  quantity  of  ash,  fat,  crude  fiber,  protein, 
and  pentosans.  The  color  of  red  rice  is  located  in  the  seed 
coat,  or  throughout  the  endosperm. 

Milling  of  Rice.' — The  threshed  rice  from  the  field  is  called 
"paddy  rice."  The  grains  are  enclosed  by  the  glumes, 
lemma,  and  palet,  which  together  constitute  the  "hull." 
The  hulls  are  removed  by  passing  the  grains  between  revolv- 
ing millstones,  set  apart  about  two-thirds  the  length  of  a  rice 
kernel.  The  hulls  are  then  removed  by  a  fanning  device,  and 
this  process  followed  by  the  separation  of  the  rough  (un- 
hulled)  from  the  clean  rice  in  the  "paddy  machine."  The 
next  process  removes  a  part  of  the  bran  layer  (pericarp,  testa 
and  nucellus)  and  most  of  the  embryo.  After  a  separation 
of  the  powdery  bran  from  the  cleaned  rice,  the  grains  are  then 
led  into  the  "pearHng  cone"  where  they  are  scoured.  This 
is  followed  by  a  thorough  poHshing  between  pieces  of  pigskin. 
The  grains  then  receive  a  coating  of  glucose  and  talc,  and  are 
ready  to  be  graded  and  packed  for  the  market. 


2o6  BOTANY  OF  CROP  PLANTS 

Beriberi. — ^This  is  a  disease  resulting  from  a  diet  consisting  chiefly  of 
polished  rice.  Asiatic  laborers  who  have  been  fed  upon  polished  rice  develop 
this  disease,  while,  if  the  rice  is  not  polished,  the  disease  does  not  appear. 
When  rice  is  polished,  there  is  removed  a  large  proportion  of  the  phosphates  of 
the  grain,  and  hence,  when  rice  is  almost  the  sole  food,  there  is  a  deficiency 
of  phosphates  in  the  ration,  which  lack  results  in  the  disease,  beriberi.  Of 
course,  those  who  have  a  mixed  diet  get  the  requisite  amoimt  of  phosphates 
from  a  number  of  different  foods,  and  hence  may  eat  polished  rice  without  any 
lU  effects. 

Varieties. — Carleton  gives  the  following  provisional  ar- 
rangement of  wild  and  cultivated  rices : 

1 .  Oryza  granulata  (wild  rice) . 

2.  Oryza  officinalis  (wild  rice). 

3.  Oryza  sativa  (cultivated  rice), 
(fl)  utilissima. 

1.  communis  (large-kerneled  rice). 

2.  minuta  (small-kerneled  rice). 
(b)  glutinosa  (glutinous  rice). 

American  varieties  are  comparatively  few  in  number. 
Three  main  types  are  grown:  Honduras,  Carolina  and  Japan. 
The  hulls  of  Honduras  and  Japan  rice  are  yellowish-brown, 
those  of  CaroHna  rice  mostly  a  golden  yellow.  Lowland 
types  of  rice  form,  almost  exclusively,  the  sorts  grown  in 
this  country.  Japan  rice  has  smaller  grains,  a  thinner  hull, 
and  tillers  more  than  the  other  types  in  the' United  States. 
Honduras  and  Carolina  belong  to  the  communis  group,  and 
Japan  to  the  minuta  group. 

Distribution  and  Closely  Related  Species. — There  is 
is  a  great  number  of  Oryza  species  found  growing  wild  in 
tropical  regions  of  both  hemispheres.-  The  native  home 
of_^0.  sativa  is  the  warm  parts  ofAsia  and  Africa.  Culti- 
vated rice  probably  originated  in  eastern  Asia. 

In  this  country,  there  are  two  quite  common  native 
plants    termed    "rice."     These    are,  Canada   rice  {Zizania 


ORYZA    SATIVA 


207 


aquatica),  and  wild  rice  {Zizania  miliacea).  Both  are^.tall 
aquatic  grasses  belonging  to  the  same  tribe  (Oryzeae)  as 
cultivated  rice.  Both  species  of  Zizania  dilTer  from  Oryza 
in  having  monoecious  spikelets. 

Uses  of  Rice. — Rice  is  a  food  for  more  human  beings  than 
is  any  other  grain.  It  is  the  principal  food  of  the  densely 
populated  regions  of  China,  India,  and  the  neighlioring 
islands.     The  consumption-  of  rice  per  capita  in  the  United 


Fig.   77. — I-L^r>v„w.,,    ....    ...    Ar / nluils   of  C-Oi^rafhy. 

Second  Hook.  Copyright  1916.  by  Albert  I'crry  BriKkum  and  Cluirlfs  T. 
McFarlane.     American  Book  Company,  Publishers.) 

States  is  steadily  increasing.  Orientals  do  not  polish  their 
rice,  while  all  the  rice  that  comes  on  the  market  in  this  coun- 
try has  had  the  hull  removed,  and  has  been  polished.  Rice 
hulls  and  rice  flour  or  polish,  removed  in  the  miUing  process, 
are  used  as  stock  food.  Rice  straw  is  also  used  as  a  food  for 
stock,  and  in  the  manufacture  of  paper,  straw  hats,  straw- 
board,  etc.  In  Japan,  a  drink  called  "sake,"  similar  to 
beer,  is  made  from  rice. 


208 


BOTANY  OF  CROP  PLANTS 


Environmental  Relations. — Rice  has  a  climatic  range  simi- 
lar to  that  of  cotton;  it  is  seldom  raised  north  of  that  region 
in  which  the  average  summer  (June,  July,  August)  tempera- 


te «5 
o  ■»; 


2  S 
Ok, 


tJU 


5fq 


3  ^ 

■^  r:  ^ 
2  '^  ^ 

O      -  .'■^ 

I.  MO, 
00  ^-     . 


ture  is  lower  than  77°F.  It  reaches  its  best  development  in 
moist  regions.  Certain  sorts  of  upland  rice  are  planted, 
cultivated  and  harvested  like  oats.     But,  most  of  the  rice 


ORYZA   SATIVA  209 

is  raised  on  low  delta- or  alluvial  lands  that  will  permit  of 
inundation.  In  lowland  rice  culture,  flooding  of  the  field 
is  usually  resorted  to  in  order  to  hasten  germination;  after 
the  plants  have  attained  a  height  of  several  'inches,  from 
3  to  6  inches  of  water  are  turned  on  to  the  field  and  kept 
there  continuously  for  twenty,  thirty,  or  more,  days,  de- 
pending upon  the  region.  The  water  is  renewed  occasionally 
to  prevent  it  from  becoming  stagnant.  It  is  drained  off 
just  prior  to  the  ripening  of  the  grain. 

The  Production  of  Rice. — British  India  produced  62,- 
638,912,000  pounds  of  rice  in  1 914.  During  the  same  period, 
Japaii  raised  17,826,240,000  pounds,  Java  and  Madura 
(1913)  7,951,049,000  pounds,  Korea  3,678,878,000  pounds, 
the  Philippine  Islands  1,403,516,000  pounds,  Italy  741,263,- 
000  pounds,  and  the  United  States  656,917,000  pounds. 

There  are  four  commercial  rice-growing  districts  in  the 
United  States:  (i)  The  Carolina  district,  (2)  the  Texas- 
Louisiana  district,  (3)  The  Arkansas  district,  and  (4)  the 
California  district.  The  heaviest  producer  is  the  Texas- 
Louisiana  district.  Louisiana  produced  13,714,000  bushels 
of  rice  in  191 5,  or  about  one-half  of  the  total  product  for  the 
entire  United  States.  Texas  ranked  second  with  7,930,000 
bushels,  Arkansas  third  with  4,840,000  bushels,  and  Cali- 
fornia fourth  with  2,268,000  bushels. 

References 
Akemine,  M.:  On  the  Flowers  and  Flowering  of  O.  sativa.    Agric.  Gaz. 

N6gy6-Sekai,  1910-11. 
Graham,  R.  J.  D.:  Preliminary  Note  on  the  Classification  of  Rice  in  the  Cen- 
tral Provinces.     Mem.  Dept.  Agr.  in  India,  Bot.  ser.  6,  No.  7:  209-230, 

1913- 
Hector^  P.  G. :  Notes  on  Pollination  and  Cross-fertilization  in  the  Common 

Rice  Plant,  Oryza  sativa,  Mem.  Dept.  Agr.  in  India,    Bot.   ser.  VI, 

i: i-io,  1913. 
KiKKAWA,  S.:  On  the  Classification  of  Cultivated  Rice.     Imp.  Univ.  Tokyo, 

Coll.  Agr.  Bull.  Ill,  No.  2,  11-108,  191 2. 
14 


CHAPTER  XVII 
MILLET 

The  term  millet  does  not  refer  to  a .  definite  botanical 
group  (species,  genus,  or  tribe)  of  plants.  Originally  it 
applied  to  certain  species  of  grasses  belonging  to  the  genera 
ChcBtochloa  (Seiaria),  Panicum  and  Echinochloa,  which  are 
still  spoken  of  as  the  "true  millets." 

Agriculturally  speaking,  the  word  "millet"  embraces 
a  number  of  annual  cereal  and  forage  grasses  which  have 
comparatively  small  seeds,  abundant  foHage,  and  a  fibrous 
root  system.  They  are  raised  in  Europe  and  the  United 
States  for  forage  purposes  and  in  a.  number  of  Asiatic  and 
African  countries  for  human  food  as  well. 

Most  of  these  millets  belong  to  the  four  genera  Chcetochloa, 
Echinochloa,  Panicum,  and  Pennisetum,  of  the  tribe  Paniceae. 
Ragi  or  finger  millet  {Eleusine  coracana)  belongs  to  the  tribe 
Chlorideae.  It  is  grown  in  India  to  quite  an  extent  as  a 
cereal  but  has  never  attained  favor  in  the  United  States. 

Key  to  Principal  Economic  Types  (Species)  of  Millet  and  Some 
Closely  Related  Common  Weed  Grasses  ^ 

Inflorescence  paniculate;  no  involucre  below  the  individual  spikelets. 
Inflorescence  a  raceme  of  short  spikes;  empty  glumes  awned  or    awn- 
pointed,  Echinochloa  (Barnyard  millets  and  wild   barnyard    grass). 
Awns  long;  spikelets  white.     E.  crusgalli  (common  barnyard  grass). 
Awns  short;   spikelets  brown,   E.  frumentacea    (Japanese  barnyard 
millet). 
Inflorescence  a  drooping  panicle;  empty   glumes   not   awned,  Panicum 
miliaceum  (proso  or  broom-corn  millet). 

'After  Frear.  210 


MILLET  211 

Inflorescence  spic;ite;  involucre  of  bristles  below  each  spikelet. 

Grain  enclosed  in   lemma  and  palet  (the  hull)  at  maturity;  spike  loose, 
Chcclochloa  (foxtail  millet  and  foxtail  grass). 
Panicle  usually  i  centimeter  thick  or  less;  bristles  commonly    green; 

spikelets  about  2  millimeters  long,  C.  viridis  (green  foxtail). 
Panicle  usually  i  to  3  centimeters  thick;  bristles  usually  purple;  spike- 
lets,  2.5  to  3  millimeters  long,  C.  ilalica  (foxtail   millets). 
Grain  globose,  forcing  open  the  hull  as  it  matures,  and  falling   free  when 
tlireshed;  spike  dense,  Pcnniselum  glancum  (pearl  millet). 

PENNISETUM   GLAUCUM   (Pearl  MUlet) 

Stem. — The  plant.s  are  erect,  and  from  3  to  8  feet  tall. 
11ie  culms  are  cylindrical  and  pithy;  the  upper  internodes  are 
smooth,  the  upper  nodes  either  smooth  or  short-hairy. 

Leaf. — The  leaf  sheaths  are  open  and  hairy;  the  ligule  is 
short  and  fimbriated ;  the  leaf  blade  is  lanceolate,  long-pointed, 
and  long-hairy  especially  on  the  upper  side. 

Inflorescence. — This  is  a  close  cylindrical  spike  (Fig.  79), 
6  to  14  inches  long  and  -^i  to  i  inch  thick.  The  main  axis  is 
stiff  and  thick-hairy.  The  side  branches  are  hairy,  7  to  8 
millimeters  long,  and  bear  each  one  to  three  (commonly  two) 
spikelets,  which  are  surrounded  by  a  cluster  of  bristles. 
These  bristles  fall  with  the  spikelets  at  maturity. 

Spikelet  and  Flower— The  lower  glume  is  short,  broader 
than  Kmg,  and  truncate;  the  inner  glume  is  longer,  about 
one-half  the  length  of  the  spikelet,  oval,  and  three-  to  four- 
nerved.  Each  spikelet  has  two  flowers,  the  lower  stami- 
nate,  the  upper  perfect.  The  lemma  of  tiie  lower  staminate 
llower  is  oval,  and  three-  to  four-nerved;  the  palet  is  small, 
sometimes  entirely  lacking,  the  stamens  three  in  number,  and 
lodicules  absent.  The  staminate  fiower  in  the  spikelet  often 
has  both  palet  and  stamens  lacking,  and  in  some  instances 
the  spikelet  has  but  one  flower,  the  staminate  one  being  en- 
tirely lacking.  In  some  few  instances,  si)ikelets  contain  two 
I)erfect  flowers.     The   Icinnia   of   the   fertile  flower  is  oval, 


212  BOTANY  OF  CROP  PLANTS 

pointed,  and  five-  to  six-nerved;  the  palet  is  oval,  rounded 
above,  pointed,  and  thin-membranous;  lodicules  are  absent; 
there  are  three  stamens;  the  ovary  is  obovate,  smooth,  and 
with  two  style  branches. 

Pollination. — Pearl    millet    is    regularly    cross-pollinated. 
The  llowers  near  the  middle  of  the  intlorescence  are  the  first 


Fk;.    79. —  Millets,      i,  Common;  2,  Hungarian;  3,  Siberian;  4,  Cmldcn  Win- 
der; 5,  Japanese  Barnyard;  6,  German;  7,  Pearl. 


to  open.  The  stigmas  of  perfect  llowers  first  appear  be- 
tween the  closed  glumes,  then  the  stamens,  which  are  in  turn 
followed  by  the  appearance  of  staminate  flowers. 

Mature  Grain. — The  kernel  is  3  to  4  millimeters  long,  reach- 
ing the  length  of  the  glumes,  obovate,  somewhat  iiattened  on 


MILLET 


213 


the  sides,  and  smooth.  One  layer  of  aleurone  cells  is  present. 
The  kernel  is  easily  separated,  as  a  rule,  from  the  lemma  and 
palet. 

Varieties. — ^There  is  considerable  variation  in  length  and 
thickness  of  the  inflorescence,  color  of  inflorescence,  and  color 
of  grain.  No  varietal  classirtcation 
has  been  made.  Pearl  millet  is 
sometimes  sold  under  the  name  of 
"  Pencilaria"  (Penicillaria)  or 
Mand's  Wonder  Forage  Plant. 
There  are  many  common  names  for 
Pearl  miflet,  some  of  which  are  cat- 
tail millet,  African  millet,  Indian 
millet,  Egyptian  miflet,  horse  millet, 
and  Japan  millet. 

Origin. — The  wild  form  from  which 
pearl  millet  has  come  is  unknown. 
It  is  probable  that  tropical  Africa  is 
its  native  home. 


PANICUM  MILIACEUM  (Proso,  Hog  or 
Broom-corn  Millet) 


Fig.  80. — Leaf  of  proso 
millet  (Panicum  milia- 
ceum).      X  2. 


Stem. — The  plants  are  erect,  some- 
limes  decumbent  at  the  base,  and 
often  reach  a  height  of  3  to  2,}4  feet. 
Branches  frequently  arise  from  the  basal  nodes,  and  they 
may  hear  inflorescences.  The  culms  are  cylindrical,  and 
rough-hairy  or  smooth  below  the  nodes. 

Leaf  (Fig.  80). — The  leaf  sheaths  are  ()j)en.  They  are 
co\'ered  with  very  small  pn^tuberances  (papillte)  from  each 
of  which  arises  a  stiff  hair;  at  the  sheath  nodes  the  hairs  are 
shorter  and  not  mounted  upon  papillae.  The  ligule  is  short, 
thick,  and  fimbriated,  and  the  auricles  are  lacking.     The  leaf 


214 


BOTANY  OF  CROP  PLANTS 


blade  is  linear  lanceolate,  and  hairy,  especially  upon  the  upper 
surface. 

Inflorescence. — This  is  a  rather  dense  panicle  (Fig.  8i), 
4  to  lo  inches  long;  the  erect  or  ascending  branches  are  some- 


FiG.   81. — Inlloresccncc  of  proso  millet  (Panicum  miliaceum). 


what  angled  and  rough  with  short  hairs  that  point  forwards. 
In  some  varieties,  the  branches  of  the  panicle  spread  to  all 
sides,  in  others  they  are  more  or  less  compressed  and  one- 
sided, while  in  a  few  varieties,  the  panicle  is  much  compressed, 
thick,  and  erect. 


MILLET  215 

Spikelet  and  Flower. — The  spikelets  are  oval  in  shape  and 
4^^  to  5  mm.  long.  The  lowermost  glume  is  broad,  pointed, 
five-  to  seven-nerved,  and  about  one-half  the  length  of  the 
spikelet;  the  second  glume  is  the  length  of  the  spikelet  and 
bears  13  nerves.  Within  the  second  (longer)  glume  is  the 
lemma  of  a  sterile  flower;  this  lemma  is  slightly  shorter  than 
the  glume  surrounding  it,  and  encloses  a  very  small  palet. 
Above  this  sterile  flower,  is  a  perfect  one.  The  lemma  of  this 
is  parchment-like,  broad,  and  seven-nerved;  it  encloses  the 
three-nerved  palet.  The  two  lodicules  are  fleshy,  smooth, 
and  somewhat  broader  than  long.  Stamens  are  three  in 
number.     There  are  two  plumose  style  branches. 

Pollination. — This  millet  is  quite  regularly  cross-polli- 
nated; however,  self-pollination  is  not  excluded. 

Mature  Grain. — The  kernel  is  firmly  surrounded  by  the 
indurated,  shining  lemma  and  palet.  The  whole  grain 
measures  about  3  millimeters  in  length  and  2  millimeters 
in  width.  The  kernel  itself  is  broadly  oval,  smooth,  white, 
and  does  not  possess  a  groove  or  furrow  as  does  wheat.  The 
position  of  the  embryo  is  indicated  by  a  shallow  broad 
marking  about  one-half  the  length  of  the  kernel.  The 
wall  of  the  kernel  is  thin.  There  is  one  row  of  small,  flat 
aleurone  cells  surrounding  the  starchy  endosperm. 

Varieties. — Koernicke  recognizes  three  main  types  of 
broom-corn  millet.     These  are  as  follows: 

1.  Panicum  miliaceum  efusum. — Panicle  broad,  the 
branches  spreading  to  all  sides. 

2.  Panicum  miliaceum  contractum. — Panicle  less  spread- 
ing than  preceding,  one-sided. 

3.  Panicum  miliaceum  compacium. — Panicle  compact, 
thick,  and  erect. 

Origin. — The  native  home  of  Panicum  miliaceum  is  not 


2l6 


BOTANY  OF  CROP  PLANTS 


known.     The   plant   has   been   cultivated   in   Europe   and 
Asia  from  the  earliest  times. 

CH^TOCHLOA  ITALICA  (Foxtail  MiUets) 

Stem.— The  plants  are 
erect  and  from  2  to  5  feet 
tall.  The  culms  are  cylin- 
drical; they  may  branch  near 
the  base,  but  such  branches 
seldom  produce  flowers  and 
fruit. 

Leaf. — The  leaf  sheaths 
are  open,  and  smooth  or 
hairy.  The  ligule  is  short, 
thick,  and  fimbriated;  auri- 
cles are  absent.  The  leaf 
blades  are  long,  broad,  and 
taper  to  a  sharp  point. 

Inflorescence. — The 
spikes  (Fig.  79)  are  4  to  9 
inches  long,  and  3^  to  2  inches 
thick.  The  chief  axis  of  the 
inflorescence  and  the  short 
side  branches  are  hairy.  On 
the  short  lateral  branches, 
there  occur  bristles  (Fig.  82) 
subtending  the  spikelets. 
These  bristles  bear  short 
hairs  that  point  forward. 
There  is  evidence  that  they 
are  abortive  branches.  It 
has  been  noted  that  varieties 

apparently  without  bristles,  occasionally  bear  spikelets  with 

bristles.        1 


Ijt  glume 
bristles 


Fig.  82. — Spikelet  of  foxtail  millet 
(Chaetochloa  italica).     X  15. 


MILLET 


217 


Spikelets  and  Flower. — The  spikelets  are  elliptical,  and 
usually  shorter  than  the  bristles,  which  subtend  them. 
Each  spikelet  (Fig.  83)  has  two  flowers,  the  lower  ster- 
ile, the  upper  with  both  stamens  and  pistil.  The  lower- 
most glume  is  oval,  pointed,  three-nerved,  and  about  one- 
third  the  length  of  the  spikelet.  The  second  glume  is 
five-nerved,  and  sHghtly  shorter  than  the  spikelet;  it  sur- 
rounds the  lemma  of  the  sterile  flower.  The  lemma  of 
the  fertile  flower  is  broad-oval,  and  five-nerved;  the  palet 
is  about  the  same  length  as  its  lemma.     Both  lemma  and 


glume      sterile  flower 


'jeriilejh 


ower 


Fig.  83. — Dissected  spikelet  of  common  millet  (Chaetochloa  italica).      X  lo. 


palet  of  the  fertile  flower  are  smooth,  shining,  hardened 
structures.  The  lodicules  are  fleshy.  There  are  three 
stamens.  The  ovary  is  long-oval  and  smooth;  its  style  has 
two  long  branches,  with  the  rudiment  of  a  third. 

Pollination. — Cross-pollination  is  the  rule;  self-pollination 
occasionally  occurs. 

Mature  Grain  (Fig.  84) . — The  lemma  and  palet  enclosie 
the  mature  kernel.  The  grain  is  oval,  shining,  2  to  2}^  milli- 
meters long  and  i>^  to  i^  millimeters  wide.  The  kernel  is 
broad-oval,  smooth,  and  white;  it  does  not  have  a  groove  or 
furrow.     The  position  of  the  embryo  is  indicated  by  a  mark 


2l8 


BOTANY  OF  CROP  PLANTS 


which  is  about  one-half  the  length  of  the  kernel.  The  peri- 
carp is  thin.  There  is  a  single  row  of  small,  flat  cells  in  the 
aleurone  layer. 

Types  and  Varieties  of  Foxtail  Millet. — Koernicke  rec- 
ognizes two  main  groups  of  cultivated  millets  belonging  to 
the  species  Chcetochloa  italica: 


Fig.  84. — A,  grain  of  foxtail  millet  (Chsetochloa  italica)  with  lemma  and 
palet  attached;  B,  grain  of  same,  embryo  side  with  "hull"  removed;  C,  grain 
of  same,  side  opposite  the  embryo;  D  and  E,  grains  of  pearl  millet  (Pennisetum 
spicatum).      X 10. 


I.  Chcetochloa  italica  maximum. — Heads  long,  open, 
and  drooping.  This  group  has  two  subdivisions:  (i) 
varieties  with  short  bristles,  and  (2)  varieties  with  long 
bristles.  Here  would  be  included  Aino  millet,  German  mil- 
let, Golden  Wonder  millet,  and  Siberian  millet. 


MILLET  219 

2.  Chcetochloa  italica  moharium. — Heads  short,  thick, 
erect,  or  drooping  but  very  slightly.  This  group  also  has  two 
subdivisions:  short-bristle  and  long-bristle  varieties.  Here 
belongs  Hungarian  millet. 

Key  to  Principal  Types  of  Foxtail  Millets  (Ciletochloa  italica)  1 

Heads  small,  uniform,  compact,  seeds  yellowish  to  black  with  usually  a 
large   percentage   very  dark;  beards  brown  or  purple,  Hungarian  Millet. 
Heads  large,  more  or  less  open;  seeds  more  or  less  bunched. 
Heads  long,  slender,  very  open,  lax,  drooping;  seed  groups  very  distinct, 

Aino  Millet. 
Heads  shorter  and  plumper,  bushy,  erect  or  slightly  drooping;  seed  groups 
indistinct. 
Seeds  yellow. 
Profusely  bearded;  medium  large  heads. 
Heads  large,  seeds  small,  seed  groups  more  distinct,  German  Millet. 
Heads  small,  seeds  large,  seed  groups  less  distinct,  Common  Millet. 
Sparingly  bearded;  heads  very  large,  Golden  Wonder  Millet. 
Seeds  red  or  pink,  Siberian  Millet. 

Origin  of  Foxtail  Millet. — The  stem  form  of  the  foxtail 
millets  is  Chcetochloa  viridis,  the  green  foxtail.  It  differs 
from  the  cultivated  forms  in  that  its  fruit  falls  from  the 
inflorescence  when  mature.  Chcetochloa  viridis  is  a  native 
of  the  Old  World.  It  is  now  found  in  waste  places  in  North 
America  from  Texas  to  Quebec. 

ECHINOCHLOA    CRUS-GALLI    (Barnyard    Grass  or   Barnyard    Millet) 

Habit,  Stems,  Leaves. — This  grass  is  an  annual,  2  to  4  feet 
tall;  the  culms  often  branch  at  the  base.  The  leaves  are  3^  to 
2  feet  long,  ^  to  i  inch  wide,  and  have  smooth,  glabrous 
sheaths  and  smooth  or  scabrous  blades. 

Inflorescence,  Spikelet,  Flowers,  and  Fruit.— The  inflores- 
cence is  a  panicle  made  up  of  from  five  to  fifteen  sessile,  erect 
or  ascending  branches;  the  lower  branches  may  be  spreading 

^  After  Frear. 


220  BOTANy  OF  CROP  PLANTS 

or  reflexed.  The  spikelets  •  are  ovate,  green  or  purple,  and 
densely  crowded  in  two  to  four  rows  on  one  side  of  the  rachis. 
Each  spikelet  has  two  flowers:  a  lower  staminate,  and  an 
upper  perfect.  Within  the  two  empty  glumes  is  the  lemma 
of  the  staminate  flower;  then  follow  the  lemma  and  palet  of 
the  perfect  flower,  both  of  which  are  hard  and  parchment-like 
in  texture.  The  lemma  of  the  staminate  flower  is  awned, 
that  of  the  perfect  flower  abruptly  pointed.  There  are  three 
stamens,  and  two  plumose  stigmas.  The  kernel  is  firmly 
surrounded  by  the  hardened  lemma  and  palet. 

Distribution. — Barnyard  grass  is  a  native  of  Europe.  It 
is  now  widely  distributed  as  a  weed  in  cultivated  soil  and  in 
waste  places. 

ECmNOCHLOA  FRUMENTACEA   (Japanese  Barnyard  MiUet) 

In  general  characters,  Japanese  barnyard  millet  corre- 
sponds very  closely  to  common  barnyard  millet,  except  that  in 
the  main,  it  has  a  more  nearly  erect  habit,  more  turgid  seeds, 
is  awnless,  or  has  very  short  awns,  and  is  brown  or  purplish  in 
color.  It  is  known  as  Sanwa  millet  in  India,  and  "billion- 
dollar  grass"  in  the  United  States.  It  probably  originated 
from  common  barnyard  millet  {E.  crusgalli). 

Environmental  Relations. — The  millets  require  environ- 
mental conditions  similar  to  those  favoring  sorghums.  They 
are  sensitive  to  cold,  and  hence  must  be  planted  after  all 
danger  from  frost  is  over.  The  water  requirement  of  millets, 
as  a  group,  is  less  than  that  of  sorghums.  Hence  they  are 
among  our  most  drought-resistant  crops,  and  on  this  account, 
have  been  cultivated  extensively  on  the  Great  Plains,  from 
Kansas  to  Dakota. 

Uses  of  Millets. — The  millets  are  grown  as  a  hay  crop,  for 
pasturage  purposes,  and  for  the  seeds,  which  are  most 
commonly  fed  to  poultry.     Millet  is  a  quick-growing  crop, 


MILLET  221 

and  is  ready  to  cut  for  hay  in  from  six  to  ten  weeks  after  seed- 
ing. The  foxtail  millets  are  more  valuable  for  hay  than  the 
proso  group.  The  latter  is  most  frequently  grown  for  the 
grain. 

References 

Ball,  Carleton  R.:  Pearl  millet  (Pennisetum  spicatum).     U.  S.  Dept.  Agr. 
Farmers'  Bull.  i68:  1-16,  1903. 


CHAPTER  XVIII 

PHLEUM  PRATENSE  (Timothy) 

Description.^ — Common  timothy  is  a  perennial  grass,  from 
iM  to  5  feet  high.  Corms  or  bulbs  form  in  the  lower  leaf 
axils,  a  single  seedhng  sometimes  having  from  eight  to  twenty. 
These  bulbs  develop  in  the  fall  of  the  year,  Uve  through  the 
winter,  and  send  up  new  shoots  the  following  season.  Thus 
we  see  that  the  plant  reproduces  vegetatively  as  well  as  by 
seeds.  In  cultivation  the  plant  shows  marked  variation  in 
stem,  leaf,  and  inflorescence  characters,  in  earhness,  duration 
of  bloom,  longevity,  vigor,  stoohng  power,  disease  resistance 
and  yield  of  hay  and  seed.  The  leaves  are  flat,  and  three  to 
eight  per  stem;  the  upper  sheaths  are  long,  usually  exceeding 
the  internodes,  and  shghtly  inflated;  the  ligule  is  rounded. 
The  inflorescence  is  cylindrical  and  spicate;  although  it  is 
often  called  a  spike,  it  is  in  reality  a  contracted  panicle.  The 
spikelets  are  one-flowered.  Each  spikelet  is  subtended  by 
two  membranous,  compressed  glumes  which  are  ciliate  on  the 
margins  (Fig.  85),  truncate  at  the  tip  and  awned;  the  lemma 
is  much  shorter  and  broader  than  the  glumes,  thin,  truncatCj 
and  finely  toothed  at  the  apex;  the  palet  is  narrow  and  thin. 
Stamens  are  three  in  number.  There  are  two  distinct  styles 
with  plumose  stigmas.  The  whole  process  of  blooming  and 
dehiscence  of  anthers  takes  place  in  about  one  and  one-half 
hours.  Clark  observed  that  the  average  number  of  days  the 
individual  heads  remain  in  bloom  varies  from  seven  to  ten. 
The  upper  third  of  the  head  blooms  first.  The  time  of  bloom- 
ing is  just  before  daybreak.     The  egg-shaped  grain  is  enclosed 


PHLEUM  PRATENSE 


223 


by  the  lemma  and  palet.     Self-fertilization  usually  occurs  in 
timothy,  although  cross-fertilization  may  also  take  place. 

It  is  customary  to  cut  timothy  while  it  is  in  bloom  or  just 
past  bloom,  for  at  this  time  the  yield  of  dry  matter  is  greater 
than  at  any  other  stage  of  maturity.  This  is  due  to  the  loss 
of  leaves  and  the  movement  of  food  materials  to  the  roots 
which  follow  the  blooming  period. 


Fig.  85. 


-Timothy  (Phleum  pratense).     A,  single  spikelet;  B,  spikelet  with 
glumes  removed;  C,  pistil. 


Environmental  Relations. — Timothy  thrives  best  in  a  moist 
and  cool  climate;  it  is  not  grown  south  of  the  36°  latitude, 
except  at  high  elevations.  It  is  unable  to  endure  hot,  dry 
summers,  such  as  exist  in  the  Great  Plains  and  intermountain 
areas.  It  is  an  important. crop  at  high  altitudes  in  the  Rocky 
Mountains,  where  it  is  usually  mixed  with  Alsike  clover. 

It  will  grow  on  both  clay  and  loam  soils,  and  does  best 
when  lime  is  present. 

Closely  Related  Species, — Mountain  timotliy  {Phleum  alpinum)  is  common 
in  meadows  from  Labrador  to  Alaska,  in  the  mountains  of  both  the  East  and 
the  West,  also  Europe,  Asia,  and  temperate  South  America.     The  inflores- 


224  BOTANY  OF  CROP  PLANTS 

cences  are  much  shorter  than  those  of  common  timothy,  the  awn  is  about  one- 
half  the  length  of  the  outer  glume,  and  the  upper  leaf  sheath  is  inflated. 

References 

Clark,  Charles  F.:  Variation  and  Correlation  in  Timothy.     Cornell  Agr. 

Exp.  Sta.  Bull.  279:  1-350,  J910. 
Observations  on  the  Blooming  of  Timothy.     Plant  World,   14:  131-136, 

1911. 
Webber,  H.  J.:  The  Production  of  New  and  Improved  Varieties  of  Timothy 

U.  S.  Dept.  Agr.  Bur.  Plant  Ind.  Bull.  313:  339-381,  1912. 


CHAPTER  XIX 
SACCHARUM  OFFICINARUM  (Sugar  Cane) 

Habit,  Roots. — Sugar  cane  is  a  tall,  perennial  plant,  re- 
sembling corn  and  the  sorghums  in  general  habit.  The  root 
system  is  hbrous  and  rather  shallow. 

Stems. — The  stem  is  of  the  usual  grass  type — divided 
into  a  number  of  joints.  The  cylindrical,  solid  culm  is 
8  to  15  feet  high,  and  i  to  2  inches  in  diameter.  There  are 
sometimes  as  many  as  60  to  80  nodes.  The  jointed  stem  is 
prolonged  into  the  ground,  and  the  roots  arise  from  the  lower- 
most nodes.  This  stem  arises  from  the  rootstock  of  the  pre- 
vious year,  or,  under  artificial  conditions,  from  the  planted 
portion  of  a  cane.  The  buds  are  found,  as  usual,  in  the  leaf 
axils.  They  are  better  developed  in  the  lower  leaf  axils 
than  in  the  upper.  Around  the  culm,  at  the  bud,  are  several 
rows  of  dots;  roots  arise  from  these  dots  when  the  cane  is 
planted,  or  when  in  any  way  it  is  brought  into  contact 
with  the  soil.  Sugar  cane  "suckers"  readily.  The  plant  is 
propagated  entirely  from  stems.  The  whole  stalk  may  be 
used  or  only  the  lower  parts  of  the  stools,  the  so-called 
''rattoons." 

Leaves. — There  is  a  single,  broad,  clasping  leaf  at  each 
node. 

Inflorescence,  Flowers,  Fruit.-  'J  he  inflorescence  is  a  loose 
panicle,  i  foot  or  more  in  length,  with  numerous  branches. 
The  spikelets  are  arranged  in  a  racemose  fashion  on  slender 
branches.  They  occur  in  pairs,  one  of  which  is  pedicellate, 
the  other  sessile.  There  are  two  glumes  at  the  base  of  the 
15  225 


226 


BOTANY  OF  CROP  PLANTS 


spikelet.  Each  spikelct  is  two-flowered;  the  lower  one  is 
sterile  and  consists  of  a  palet;  the  upper  is  fertile  and  has 
a  lemma  and  palet,  two  minute  lodicules,  one  to  three  sta- 
mens, and  a  single  ovary  with  two  stigmas.  There  is  a  tuft 
of  long,  silky  hairs  at  the  base  of  each  spikelet.     The  grain 


Fig.  86. —  Mill  where  sugar  cane  is  crushed.  (From  Essentials  of  Geography  _ 
Second  Book.  Copyright,  1916.  by  Albert  Perry  Brigham  and  Charles  T 
McFarlane.     American  Book  Company,  Publishers.) 


is  small,  silky,  and  of  low  vitaUty.  Mature  grains  are  seldom 
produced  in  cultivated  plants  and  pollen  is  often  infertile. 
Geographical.^ — Saccharum  officinarum  is  a  native  of  the 
tropics.  It  is  now  grown  as  a  crop  throughout  our  Southern 
States  and  in  many  other  warm  regions.     It  is  not  a  success 


SACCHARUM   OFFICINARUM  227 

north  of  the  latitude  of  33°.  The  roots  are  unable  to  stand 
a  temperature  much  lower  than  i5°F. 

Sugar  from  Sugar  Cane. — The  canes,  stripped  of  their 
leaves,  are  first  shredded  by  revolving  spiked  cylinders,  and 
then  passed  between  three  different  sets  of  rollers,  which 
crush  out  the  juice.  About  75  per  cent,  of  the  juice  is  pressed 
out  by  the  first  set  of  rollers.  Between  the  first  and  second 
set  of  rollers,  the  canes  are  sprayed  with  the  heated  juice  from 
the  third  set.  About  10  per  cent,  of  the  total  amount  of 
juice  is  removed  by  the  second  set  of  rollers.  Before  reach- 
ing the  last  set  of  rollers,  the  crushed  material  is  sprayed  with 
hot  water;  in  this  process  about  5  per  cent,  of  the  total  juice 
is  removed.  The  crushed  canes,  known  as  "bagasse," 
are  utiHzed  as  a  fuel  to  run  the  mill. 

The  juice  that  flows  from  the  rollers  is  turbid,  due  to 
the  impurities  which  it  contains.  It  is  strained,  and  then 
milk  of  Hme  is  added.  The  Hmed  juice  is  heated  with  steam. 
The  impurities  unite  with  the  lime,  and  appear  as  scum  on 
top  or  as  a  sediment  at  the  bottom  of  the  purified  juice. 
The  clear  juice  is  run  into  vacuum  evaporators,  where  it  is 
concentrated  to  the  desired  point.  The  concentrated  juice 
is  then  pumped  into  tanks,  where  crystallization  is  brought 
about. 

The  grain  of  the  sugar  is  under  the  control  of  the  one 
who  has  the  crystallizing  pans  in  charge.  A  high  temper- 
ature in  the  vacuum  pans  favors  the  formation  of  hard- 
grained  sugar;  while  a  low  temperature  and  high  vacuum 
produce  a  "soft  sugar."  The  mixture  of  molasses  and  sugar 
crystals  is  termed  "massecuite."  They  are  separated  by 
centrifugal  action.  The  sugar  crystals  are  then  dried,  and 
packed  for  shipment. 

By-products  of  Manufacture. — Cane  molasses  from  the 
manufacture  of  white  and  high-grade  yellow  sugars  is  used  for 


228  BOTANY  OF  CROP  PLANTS 

baking  purposes  and  as  a  table  syrup.  Poorer  grades  are 
employed  in  rum  and  alcohol  manufacture,  and  in  stock 
feeding. 

Mention  has  been  made  of  the  fact  that  the  stalks  from 
which  the  juice  has  been  removed  are  used  as  a  fuel  to  run 
the  mill.  The  refuse  that  accumulates  in  the  purification 
process  is  used  as  a  fertihzer.  It  is  rich  in  phosphorus  and 
potash. 

Production  of  Cane  Sugar.^The  world's  production  of 
cane  sugar  during  the  1913-1914  campaign  was  11,225,000 
short  tons  (excluding  Central  America).  During  the  same 
period,  the  world  production  of  beet -sugar  was  9,430,145 
short  tons.  Sugar-cane  production  in  the  United  States  is 
confined  almost  exclusively-  to  southern  Louisiana,  and  to 
Texas,  immediately  adjoining. 

Leading  Countries  in  the  Production  of  Cane  Sugar,  1913-1914 

Country  Short   tons 

Cuba 2,909,000 

British  India 2,566,000 

Java 1,541,000 

Hawaii 61 2,000 

Philippine  Islands 408,000 

Australia  and  Fiji 407,000 

Porto  Rico 364,000 

Argentina 304,000 

United  States 301,000 

Mauritius 275,000 


CHAPTER  XX 
LILIACEiE  (Lily  Family) 

Representatives  of  the  lily  family  are  found  all  over  the 
world,  although  the  family  is  best  developed  in  drier  parts  of 
the  temperate  zone.  The  family  is  by  no  means  of  as  great 
economic  importance  as  the  grass  family.  A  number  of 
representatives  are  cultivated  as  vegetables,  the  principal 
ones  being  onions,  and  asparagus.  Yucca,  lily  (Lilium), 
hyacinth  and  tuHp  are  chief  among  those  cultivated  as 
ornamentals. 

Habit,  Roots. — Most  members  of  the  family  are  fleshy 
herbs  from  bulbs  or  rhizomes.  Some  species  of  Aloe  and 
Draccena,  however,  are  shrubs  or  small  trees.  In  herbace- 
ous forms,  the  roots  axe  mostly  fibrous  and  shallow,  sometimes 
fleshy  and  extending  to  considerable  depths  in  the  soil. 

Stems. — Both  underground  and  aerial  stems  are  borne. 
Underground  stems  in  the  family  are  either  rhizomes  or 
bulbs.  The  character  of  rhizomes  has  been  described  (page 
29).  Bulhs  are  fleshy  stems  with  a  very  short,  usually  con- 
ical stem  upon  which  are  many  fleshy,  overlapping  leaves 
(Fig.  14).  Bulbs,  Hke  rootstocks  or  rhizomes,  are  storage 
organs.  They  are  made  use  of  in  vegetative  propagation. 
The  aerial  stems  may  be  leafy  or  free  of  leaves  for  a  long  dis- 
tance. In  Yucca — the  soapweed  or  Spanish  bayonet — of 
the  semi-arid  sections  of  the  country,  the  base  of  the  aerial 
stem  is  persistent  from  year  to  year. 

Leaves. — The  leaves  are  mostly  linear,  seldom  divided  or 
toothed,  and  not  divided  into  petiole  and  blade. 
229 


230 


BOTANY   OF   CROP   PLANTS 


Inflorescence  and  Flowers.- — There  are  a  number  of 
different  types  of  inflorescences  in  the  family.  The  flowers 
are  often  single  or  solitary,  as  in  the  Hlies;  or  racemose,  as  in 
the  soapweed  and  hyacinths ;  or  umbellate,  as  in  onion.  The 
umbellate  or  umbel-like  type  of  inflorescence  consists  of  many 
flower  stalks  of  about  equal  length  arising  near  together  on 
the  stem;  the  outside  flowers  open 
first,  the  inside  last,  that  is,  the  order 
of  opening  is  centripetal.  This  is  the 
order  of  opening  in  all  racemose  types 
of  inflorescences.  The  perianth  con- 
sists of  six  separate  segments,  in  two 
whorls  of  three  each,  which  are  very 
similar  in  size,  shape  and  color  (Figs. 
3 1  and  8  7) .  The  stamens  are  attached 
to  the  receptacle  or  to  the  perianth. 
The  anthers  are  usually  large  and  con- 
spicuous. The  superior  ovary  is 
three-celled,  has  one  style  and  a 
three-lobed  stigma. 
Fruit  and  Seeds. — The  fruit  is  a  capsule  or  berry.  The 
capsule  is  a  dry,  splitting  (dehiscent)  fruit  with  several  united 
carpels.  When  the  carpels  split  down  the  middle  line  as 
they  do  in  lilies,  the  dehiscence  is  said  to  be  loculicidal. 
It  is  distinguished  from  septicidal  dehiscence  of  capsules, 
in  which  the  carpels  open  along  the  Hne  of  their  union,  as  in 
rhododendron,  and  from  poricidal  dehiscence  in  which  the 
carpels  open  by  pores,  as  in  the  poppy.  The  herry  is  a  fleshy 
fruit  possessing  several  to  many  seeds  which  are  more  or 
less  imbedded  in  the  fleshy  ovary  wall  (pericarp). 

The  seeds  always  possess  abundant  endosperm,  which  en- 
closes the  embryo.  Considerable  quantities  of  oil  occur  in 
the  endosperm. 


Fig.  87 


Flower  of  onion 
(Allium  cepa). 


LILIACEiE 


231 


ALLIUM 
To  this  genus  belong  chives,  garHc,  leek,  onion,  shallot  and 
Welsh  onion.     They   are   all  herbs   with   a   characteristic 


Fig.  88. — A,   Welsh   onion  (Allium  ascolonicum).;  B,  cive  (Allium  schceno- 
prasum). 

alliaceous    odor,    which    is    due    to    the  presence  of  allyl 
sulphide. 


232  BOTANY  OF  CROP  PLANTS 

Roots. — The  root  system  is  fibrous  and  very  shallow  (Fig. 
88).  The  roots  arise  from  the  reduced  stem,  forming  a 
fibrous  tuft. 

Steins. — With  but  few  exceptions,  species  of  the  genus 
Allium  bear  bulbs.  In  chives  {Allium  schosnoprasum) ,  the 
bulbs  are  very  small  (Fig.  88),  and  in  Welsh  onion  (Allium 
fistulosum)  and  leek  {Allium  porrum),  they  are  nearly  always 


Fig.  89. — Leek  (Allium  porrum). 

absent  (Figs.  88  and  89) .  In  the  common  onion  {A  Ilium  cepa) , 
they  are  large  and  well  developed.  Examination  of  the 
mature  bulb  of  the  common  onion  shows  it  to  be  made  up  of 
the  much  thickened  bases  of  leaves,  attached  to  a  compara- 
tively small,  conical  stem  (Fig.  14).  This  is  best  seen  in  a 
median,  longitudinal  section.  From  a  terminal  bud  on  this 
small,  underground  stem,  there  is  sent  up  a  long  hollow  or 
solid,  leafless  stem  (Fig.  90)  (scape)  bearing  an  inflorescence 
at  the  top,  which  in  this  case  is  an  umbel.    Lateral  buds  are 


LILIACE/E 


233 


sometimes  borne  in  the  axils  of  the  leaves,  and  these  may  also 
develop  into  flower  shoots. 

Leaf.— The  first  foliage  leaf  emerges  from  a  slit  in  the 
cotyledon.  AU  leaves  are  very  thick  and  fleshy,  and  over- 
lapping.    There  is  no  petiole. 


The  oldest  leaves  are  on  the 


lM<;  00  —A,  base  of  stem  of  common  onion  (Allium  cepa)  showmg  hollow 
leaves  cut  across;  B.  cross-section  of  hollow  stem  of  same:  C.  base  of  stem  o 
leek  (Allium  porrum)  showing  flattened  solid  leaves;  D.  cross-section  of  solid 
stem  of  same. 

outside  of  the  Inill).  while  the  younger  appear  toward  the 
inside.  In  a  longitudinal  section  of  the  bulb,  it  will  be  noted 
that  these  younger  leaves,  coming  from  within,  are  higher 
on  the  compressed  stem  than  the  older  (Fig.  14)-  The 
edible  "portion  of  the  common  onion,   and  of  some  other 


234  BOTANY  OF  CROP  PLANTS 

species,  is  the  fleshy  bases  of  leaves.  In  some  species,  as 
leek  and  shallot,  the  leaves  are  used  as  a  seasoning  in  food. 
The  leaves  may  be  either  flat  or  cylindrical  (terete),  and  are 
sometimes  hollow.  Onions  have  been  known  to  bear  buds 
(epiphyllous  buds)  on  their  leaves. 

Inflorescence   (Fig.    91). — The  numerous  flowers  are   in 
simple,   terminal   umbels.     The  umbel    is  subtended    by  a 


spathc,  consisting  of  two  (rarely  three)  papery  bracts.  The 
spathe  encloses  the  entire  umbel  in  the  bud.  The  pedicels 
arc  long  and  slender. 

Flower. — The  flowers  (Fig.  87)  are  regular  and  perfect. 
The  perianth  consists  of  six  distinct  segments  which  are  very 
similar  as  to  size,  shape  and  color.  The  six  stamens  are 
inserted  on  the  bases  of  the  perianth  segments.     Alternate 


LILIACE^ 


23s 


filaments  are  usually  dilated  at  the  base,  and  the  anthers  are 
oblong,  and  opening  inward  (dehiscing  inward) .  The  single, 
superior   ovary  is  imperfectly   three-loculed   and  bears   a 


Fig.  92. — Seed  and  seedling  of  onion  (Allium  cepa).  A,  seed;  B,  to  F,  suc- 
cessive stages  in  the  development  of  the  seedling;  c,  cotyledon;  e,  endosperm; 
/,  first  true  leaf;  h,  hypocotyl;  j,  slit  from  which  the  first  true  leaf  emerges.  A 
considerably  magnified.     {After  Bergen  and  Caldwell.) 

single  fihform  style,  which  may  be  more  or  less  indistinctly 
three-cleft  at  the  apex. 

Pollination. — Species  of  Allium  are  insect  pollinated.  The 
anthers  of  the  flower  usually  mature  before  the  stigma,  al- 


236  BOTANY  OF  CROP  PLANTS 

though  the  reverse  is  sometimes  the  case.  The  inner  circle 
of  stamens  is  the  first  to  shed  pollen. 

Fruit. — This  is  a  three-celled,  membranaceous  capsule 
with  locuHcidal  dehiscence.  Two  seeds,  black  in  color, 
are  usually  borne  in  each  locule  of  the  capsule.  The  seeds 
(Fig.  92)  are  convex  on  one  side  and  almost  flat  on  the  other, 
and  possess  a  large  quantity  of  oil.  The  embryo  is  cylin- 
drical and  curved. 

Germination  of  Seed,  and  the  Seedling. — At  the  beginning 
of  germination,  the  primary  root  is  forced  out  by  the  growth 
of  the  curved  end  of  the  embryo  (Fig.  92).  The  curved 
end  of  the  embryo,  the  cotyledon,  comes  out  of  the  ground 
in  the  form  of  a  closed  loop.  The  tip  of  the  cotyledon  re- 
mains attacked  to  the  endosperm  and  seed  coat.  When  the 
soil  is  loose,  the  endosperm  and  seed  coat  may  be  pulled 
from  the  ground,  but  in  case  it  is  compact,  they  remain 
beneath  the  ground.  The  cotyledon  absorbs  nourishment 
from  the  endosperm.  When  this  is  used  up,  the  cotyledon 
tip  withers  and  becomes  detached  from  the  seed  coat.  At 
the  base  of  the  cotyledon,  where  it  joins  the  hypocotyl,  there 
early  appears  a  longitudinal  sHt;  through  this,  the  first 
foliage  leaf  emerges.  The  cotyledon  later  disappears 
entirely. 

Geographical. — There  are  about  250  species  of  the  genus 
Allium,  the  majority  of  which  occur  in  boreal  America, 
Mexico  and  northern  Europe.  A  number  are  also  found  in 
Abyssinia  and  extratropical  Asia.  The  cultivated  onions 
require  cool,  moist  weather  during  the  early  stages  of  their 
development,  but  ripen  better  if  the  weather  is  drier. 

Key  to  Principal  Cultivated  Species  of  Genus  Allium 

Leaves  flat  and  solid  (Fig.  90). 

Leaves  keeled,  very  narrow,  Allium  salivum  (garlic). 
Leaves  keeled,  very  broad,  Allium  porrum  (leek). 


LILIACEiE 


237 


Leaves  cylindrical  and  hollow  (Fig.  90). 

Plants  forming  a  dense  clump    with  very    small  bulbs,  Allium  schceno- 

prasum  (cive  or  chives). 
Plants  not  forming  dense  clumps;  bulbs  of  considerable  size. 
Leaves  short,  awl-shaped;  bulbs  in  clusters  (Fig.  88),  Allium  ascaloni- 

cum  (shallot) 
Leaves  long,  rather  broad;  bulbs  not  in  clusters. 

Bulbs  very  distinct,  generally  large  (Fig.  14),  Allium  cepa  (common 

onion) . 
Bulbs  not  distinct,  usually  a  mere  swelling  at  base  of  plant  (Fig.  88). 
Allium  fistulosum,  (Welsh  onion,  ciboule). 


ALLIUM  SATIVUM  (GaiUc) 


Garlic  is  a  perennial  herb.  The  bulbs  are  composed  of 
several  small,  elongated,  egg-shaped  bulbils,  called  "cloves," 
all  of  which  are  enclosed  by  a 
whitish  skin  .(Fig.  93).  There 
are  often  as  many  as  ten  bulbils 
in  a  single  bulb.  The  scape  is 
from  I  to  2  feet  high,  round, 
and  possesses  alternate,  broad- 
linear,  sohd,  flat  leaves.  The 
spherical  umbels  bear  many 
bulblets  among  the  small,  long- 
stemmed  flowers.  Seeds  and 
bulblets  are  borne  in  the  same 
head.  In  propagation,  the  bulb- 
lets in  the  flower  head  and  the 
Fig.  93.— Bulb  of  garlic  (Allium    cloves  are  used  more  commonly 

sativum).     X  M-  ,  , 

than  seeds. 
GarHc  is  a  native  of  southern  Europe.     Both  the  cloves 
and  leaves  are  used  in  seasoning  salads  and  soups,  and  the 
stems  are  also  often  an  ingredient  of  sausage  and  other  ground 
meats. 


238  BOTANY   or   CROP  PLANTS 

ALLIUM  PORRUM  (Leek) 

Leek  is  a  very  robust  biennial  plant.  The  bulbs  are 
small.  The  tall  scape  is  solid  and  bears  broad,  solid,  keeled 
leaves  (Fig.  90). 

Leek  is  a  native  of  the  Mediterranean  region. 

The  edible  portions  of  the  plant  are  the  bases  of  stems  and 
leaves.  The  stems  are  blanched  and  eaten  the  same  as  aspara- 
gus or  as  common  onions.  The  leaves  are  used  to  season 
soups,  salads  and  stews. 

Important  varieties  are  Large  American  Flag,  Mussel- 
burgh, Large  Rouen  and  Monstrous  Caratan. 

ALLIUM  SCHCENOPRASUM  (Chives  or  Gives) 

Chives  (Fig.  88)  are  hardy  perennials  bearing  small, 
white,  narrowly  ovoid,  clustered  bulbs  with  membranous 
coats.  The  scape  is  stout  and  up  to  2  feet  high.  The  leaves 
are  Hnear,  terete,  and  hollow,  7  or  8  inches  in  length  and  borne 
in  dense  tufts.  The  rose-colored  flowers  are  in  dense,  globu- 
lar umbels.  Although  the  plant  flowers  profusely,  it  seldom 
produces  seeds.  It  is  propagated  by  division  of  the  tufts  of 
bulbs. 

Chives  are  natives  of  Europe,  Asia  and  North  America. 
In  this  country,  they  grow  wild  from  New  Brunswick  to 
Alaska,  south  to  Maine,  northern  New  York,  Michigan, 
Wyoming  and  Washington. 

The  young  leaves  are  used  in  the  seasoning  of  soups,  ome- 
lets, and  stews.  The  plants  are  also  used,  ornamentally,  in 
garden  borders.  . 

ALLIUM  ASCALONICUM  (ShaUot) 

This  is  a  perennial  herb  with  small,  oblong-pointed  bulbs 
about  I  inch  in  diameter  and  2  inches  long  (Fig.  94).     The 


LILIACEiE  239 

bulbs  are  borne  in  clusters,  but  unlike  garlic,  are  not  sur- 
rounded by  a  thin  membrane.  The  leaves  are  short,  cylin- 
drical and  hollow.  The  compact  umbels  bear  lilac  or  reddish 
flowers. 


Fig.  94. — Shallot  (Allium  ascolonicum), 
ALLIUM  FISTULOSUM  (Welsh  Onion  or  Ciboule) 

This  is  an  annual  or  biennial  with  long,  fibrous  roots.  No 
bulbs  are  produced,  mere  swellings  occurring  at  the  base  of 
the  plant  (Fig.  88) .  The  leaves  are  long,  rather  broad  and 
hollow.     It  seeds  well. 

The  plant  has  been  found  wild  about  the  Altai  Mountains 
and  Lake  Baical  in  Siberia.  It  is  not  known  how  the  plant 
got  its  name  "Welsh  Onion." 


240 


BOTANY  OF  CROP  PLANTS 


The  leaves  are  used  as  a  seasoning  in  stews,  soups  and 
salads. 

ALLIUM  CEPA  (Onion)  ' 

Description. — The  common  onion  is  a  biennial  with  large 
bulbs,  that  are  usually  single.  The  scape  is  2  to  3  feet  tall, 
smooth,  and  somewhat  enlarged  near  the  middle.  The  leaves 
are  long,  broad,  cyUndrical  and  hollow  (Fig.  90). 


Fig.  95. — Top  onions. 


History. — The  common  onion  is  at  present  not  found  in  a 
wild  state.  Its  cultivation  dates  back  to  the  earliest  times 
in  the  history  of  India,  Egypt,  and  China.  It  was  used  by 
Egyptians  as  a  sacrificial  offering.  By  1390,  the  onion  was 
quite  extensively  used  in  Europe.  The  earliest  colonists 
brought  the  onion  with  them  to  America. 


LILIACE^ 


241 


Types  of  Onions. — The  varieties  of  common  onions  differ 
quite  widely  as  to  manner  of  propagation,  quality,  shape, 
color  and  size  of  bulbs,  and  time  of  maturity.  L.  H.  Bailey 
proposes  a  classification  as  follows: 

1.  Propagated  by  division  {Allium  cepa  var,  muUiplicans) . 
Potato  onions. 

Multipliers. 

2.  Propagated  by  inflorescence  bulblets  or  "tops"  (Fig.  95)  {Allium  cepa 
var.  bulbellifera) . 

Top  onions. 
Tree  onions. 
Egyptian  onions. 


Fig.  96. 


-Two  common  types  of  onions  based  upon  shape  of  bulb.     A,  globe 
type;  B,  flat  type. 


3.  Propagated  by  seeds  {Allium  cepa).     (These  are  also  propagated  by 
"sets,"  which  are  small  bulbs  grown  from  seed  and  arrested  in  their  develop- 
ment.) 
Skin  of  mature  bulb  silvery  white. 

1.  Globe  onions  (Southport  White  Globe)  (Fig.  96). 

2.  Flat  onions  (Fig.  96). 

(a)  Bulbs  large  (White  Italian  Tripoli,  Silver  Skin,  White  Bermuda, 

White  Portugal). 
{b)  Bulbs  small  (Queen). 
16 


242 


BOTANY  OF  CROP  PLANTS 


Skin  of  mature  bulb  colored. 

1.  Globe  onions  (Southport,  Yellow  Globe,  Southport  Red  Globe,  Giant 
Rocco,  Golden  Ball,  Yellow  Danvers). 

2.  Flat  Onions. 

(a)  Bulbs  deep  and  distinctly  red  (Red  Wethersfield,  Red  Globe,  Red 

Bermuda). 
(6)  Bulbs  indifferent  in  color,  reddish  or  yellowish  (Yellow  Danvers, 

Prizetaker,  Strasburg). 

The  "multiplier"  onions  have  compound  bulbs  (Fig.  97), 
copper-yellow  in  color,  with  rather  thick  skin  and  mild  flavor. 
When  large  bulbs  are  planted,  they  segregate  into  a  number 
of  bulbs,  and  each  produces  six  to  twelve  stalks.     The  potato 


Fig.  97. — Cross-section  of  a  multiplier  onion  bulb.     {After  Bailey.) 

onion  is  a  hardy  "multiplier,"  sometimes  called  EngHsh 
multiplier.  The  principal  use  of  the  "multipHer"  group  is 
in  the  production  of  "  bunchers  "  for  the  early  market.  There 
are  both  white  and  yellow  "multipHers." 

In  "top,"  "tree,"  and  "Egyptian"  onions,  clusters  of  bulb- 
lets  are  produced  at  the  top  of  the  scape.  Some  primordia 
develop  into  flowers  and  others  into  bulblets.  In*  some  cases, 
all  the  primordia  may  develop  into  bulblets,  and  again,  al- 
most all  may  develop  into  flowers,  some  of  which  may  pro- 
duce fertile  seed.  Bulblets  may  be  produced  in  separate 
clusters  one  above  the  other  on  the  same  stalk.     They  may 


LILIACE^  243 

germinate  while  still  attached  to  the  inflorescence.  It  is  not 
clearly  known  what  is  the  cause  of  bulblet  formation  in 
the  inflorescence.  Egyptian  onions  are  often  called  ''peren- 
nial tree  onions.''  They  are  valued  for  fall  planting  in  the 
North  to  produce  early  spring  "bunchers."  They  are  a  hardy 
type. 

The  types  of  onions  grown  from  seed  are  also  classified  by 
Goff  and  by  Gross.  In  these  classifications,  the  primary 
divisions  are  made  on  the  basis  of  bulb  shape,  the  secondary 
ones,  on  size  and  color. 

Foreign  and  Domestic  Onions.— There  is  a  rather  sharp 
distinction  between  ''foreign"  and  "domestic"  types  of 
onions.  The  foreign  types  include  Bermuda,  Spanish  and 
Itahan  onions.  As  compared  with  American  types,  they  are 
larger,  less  hardy,  the  flesh  is  more  tender  and  mild,  but  they 
do  not  keep  as  well.  On  account  of  their  tenderness,  the 
foreign  types  of  onions  do  best  in  Florida,  Texas,  and  south- 
ern Cahfornia.  Seed  of  the  Bermuda  onion  is  produced 
successfully  only  in  Teneriffe,  one  of  the  Canary  Islands, 
off  the  west  coast  of  Africa.  Attempts  to  grow  seed  in  the 
United  States  have  given  comparatively  poor  results.  The 
Prizetaker  is  our  best  example  of  a  Spanish  onion.  Impor- 
tant varieties  of  Italian  onions  are  the  B arietta,  White 
Italian  Tripoli,  White  Rocco,  and  Giant  Gibraltar.  There 
are  numerous  varieties  of  American  onions,  well-known  ones 
being  as  follows:  .Red  Wethersfield,  Southport  Globe 
(white,  yellow  and  red),  Dan  vers,  American  Prizetaker, 
White  Portugal,  Silverkin  and  Strasburg. 

Composition  of  Onions. — Different  varieties  of  onions 
vary  as  to  flavor  and  composition.  The  foreign  types  are 
milder  than  American  types.  The  flavor  is  usually  more 
pronounced  in  bulbs  than  in  leaves  or  other  parts  of  the 
plant.     The  flavor  and  odor  of  onions  is  due  to  an  oil-like 


244  BOTANY   OP   CROP   PLANTS 

organic  compound  of  sulphur,  allyl  sulphide.  The  com- 
pound is  volatile  to  a  high  degree,  and  is  broken  down  by 
heat;  consequently  the  onion  is  milder  when  cooked  than 
when  raw.  As  a  rule,  white  varieties  are  milder  than  yellow 
and  red  kinds,  although  there  are  exceptions  to  this. 

Uses  of  Onions. — Onions  are  most  commonly  used  as  a 
vegetable,  but  in  many  instances  for  flavoring  purposes. 
The  small  varieties  such  as  Queen,  B arietta,  and  American 
Silverskin  are  used  for  pickling.  The  Egyptian  (perennial 
tree  onion)  and  multipliers  are  valued  for  the  production 
of  bunchers.  It  is  considered  that  the  allyl  sulphide  in 
onions  stimulates  the  flow  of  digestive  juices  and  hence 
they  are  often  recommended  for  those  having  a  tendency  to 
constipation.  Again,  on  account  of  the  small  amount  of 
starch  and  sugar  they  contain,  onions  are  made  a  part  of 
the  diet  of  invalids  who  are  not  allowed  starchy  foods. 

ASPARAGUS 

Generic  Description. — Members  of  the  genus  Asparagus 
are  all  perennial  plants  with  rather  fleshy  roots  and  short 
rootstocks.  From  the  latter,  arise  branching  aerial  stems, 
which  are  sometimes  annual,  as  in  the  common  edible 
asparagus  (A.  officinalis),  or  perennial  as  in  A.  laricinus, 
one  of  the  ornamental  asparagi.  The  stems  are  erect  or 
cHmbing,  in  some  instances  {A .  falcatus)  reaching  a  distance 
of  25  feet  or  more.  The  small  leaf -like  structures  along  the 
stem,  the  so-called  "leaves,"  are  in  reality  modified  stems 
(cladophylls)  (Fig.  98).  They  may  be  slender,  as  in  com- 
mon asparagus,  or  broad,  as  in  Smilax.  They  are  arranged 
in  clusters  or  whorls  in  the  axils  of  the  true  leaves.  The  true 
leaves  (Fig.  98)  are  scales  or  spines,  usually  very  small. 
They  subtend  the  branches.  The  flowers  are  solitary,  in 
small  umbels  or  racemes  and  arise  in  the  axils  of  the  scales 


LILIACE^ 


245 


or  fascicles  of  cladophylls.  Each  flower  is  mounted  on  a 
very  slender  jointed  pedicel.  The  perianth  consists  of  six 
similar  segments  which  are  separate  or  slightly  united  at 
the  base.     They  are  persistent  in  the  fruit.     Stamens  are 


Fig.  98. — Garden  asparagus  (Asparagus  officinalis).  A,  pistillate  flower; 
B,  staminate  flower;  C,  mature  fruit;  D,  section  of  fruit;  E  and  F,  portions  of 
the  plant  showing  method  of  b  anching,  position  of  flowers  and  leaves. 


six  in  number  and  inserted  at  the  bases  of  the  perianth 
segments;  the  filaments  are  distinct  and  filiform,  and  the 
anthers  are  ovate  or  oblong,  with  introrse  dehiscence.  The 
superior  ovary  is  sessile,  three-lobed,  with  a  short,  slender 
style  and  three  short,  recurved  stigmas.     The  fruit  (Fig.  98) 


246  BOTANY  or  CROP  PLANTS 

is  a  globose  berry  with  two  seeds  (sometimes  more),  in  each 
of  the  three  locules.  The  seeds  are  subglobose,  often  dark  in 
color.     The  embryo  is  cyhndrical. 

Economic  Importance  of  Genus. — The  genus  Asparagus 
contains  about  150  species  distributed  throughout  tem- 
perate and  tropical  parts  of  the  Old  World.  There  are 
numerous  ornamental  species,  the  most  common  being 
Asparagus  medeoloides  (smilax),  A.  plumosus  (the  plumy 
asparagus),  a  chmbing  plant  used  for  decorative  purposes 
and  often  called  "asparagus  fern,"  and  A.  sprengeri,  another 
"asparagus  fern,"  much  used  for  planting  in  hanging  baskets. 
The  only  edible  species  of  any  consequence  is  Asparagus 
officinalis,  the  common  garden  asparagus. 

ASPARAGUS  OFFICINALIS  (Asparagus) 

The  common  garden  asparagus  is  a  much-branched  peren- 
nial herb  reaching  a  height  of  3  to  7  feet. 

Roots. — The  roots  (Fig.  99)  are  numerous  and  fleshy,  ex- 
tending horizontally  in  the  soil  to  some  distance,  but  being 
confined  to  the  surface  layers.  They  arise  both  from  the 
sides  and  bottom  of  the  thickened  rootstock.  Each  year  new 
roots  are  produced  and  the  older  ones  die  and  become  hollow, 
without  becoming  separated  from  the  stem.  New  roots  ap- 
pear above  the  older,  which  accounts  for  the  so-called 
"Hfting"  of  the  plants. 

Stems. — Asparagus  bears  both  subterranean  and  aerial 
stems.  The  underground  stems  are  rootstocks.  They  are 
much  thickened,  branched,  rather  woody,  and  about  long 
as  broad.  The  rootstock  or  "  crown  "  makes  an  annual  growth 
of  I  to  3  inches.  Its  extension  is  horizontal,  taking  place  at 
one  or  both  ends.  The  older  portions  of  the  rootstock  gradu- 
ally die.  The  rootstocks  send  up  aerial  shoots  (Fig.  99). 
These  at  first  are  thick  and  fleshy  ("spears")  and  form  the 


LILIACE.'E 


'47 


edible  portion  ol  the  plant.  Tin'  scales  borne  on  these  llcshy 
shoots  arc  true  leaves.  At  lenthi^,  the  stems  become  much 
branched.  The  filiform  cladophylls  (Fig.  98)  are  mostly 
clustered  in  the  axils  of  the  minute  scales.  They  perform 
the  function  of  lea\es,  as  is  evidenced  by  their  green  color. 
From  the  time  of  seeding,  it  is  usually  four  years  before  the 
rootstock  is  vigorous  enough  to  allow  cuttings  to  be  made. 


Fii;.   99. — r.arden   asparagus    (Asparagus    ofTicinalis).     .1,    young    shoot    or 
"spear";  B.  thick,  fibrous  roots  and  young  shoots  arising  from  "crown." 

However,  good  crops  ha\-e  been  produced  two  years  after 
seeding.  The  plant  may  ])c.  [)ropagated  by  divison  of  the 
root  stocks,  but  the  common  method  is  by  seeding. 

Leaf. — The  true  leaves  (Fig.  98)  are  minute  scales  sub- 
tending the  whorls  of  clado[)hylls.  Thi-y  flo  not  i)erform  leaf 
functions. 

Flower. —The  llowers  are  .-^mall.  drot)i)ing,  greenish-\-i'll(jw 
and  usually  solitary,  but  sometimes  in  twos  or  more  at  the 


248 


BOTANY    OF    CROP    PLANTS 


nodes.  Each  flower  is  borne  on  a  short,  slender  jointed 
pedicel  (Fig.  ico).  The  perianth  is  campanulate  (bell- 
shaped),  about  6  millimeters  long,  the  segments  being  linear 


Fig. 


(JO. — Garden  asparagus  (.A.sparagus  officinalis).      Portion  of   pistillate 
plant  in  fruit,  on  left;  and  of  staniinate  plant  in  flower,  on  right. 


and  obtuse.  The  stamens  are  shorter  than  the  perianth 
lobes.  The  single  ovary  has  a  short  style,  a  three-lobed 
stigma  and  three  locules.     Common  asparagus  is  dioecious — 


LILIACEiE 


249 


staminate  and  pistillate  flowers  are  borne  on  different  plants. 
Hermaphroditic  flowers  sometimes  occur,  however.  The 
staminate  flowers  (Fig.  98)  are  slightly  larger  than  pistillate 
ones.  Staminate  flowers  bear  six  well-developed  stamens 
and  a  very  short,  rudimentary  pistil.  Pistillate  flowers 
(Fig.  98)  have  six  rudimentary  stamens  and  a  single  well- 
developed  pistil.  Such  flowers  are  practically  unisexual. 
It  has  been  shown  that  staminate  plants  are  more  produc- 
tive than  pistillate  ones.  Green,  in  determining  the  relative 
productivness  of  pistillate  and  staminate  plants,  obtained  the 
following  results: 

Peoduct  from  Fifty  Plants  Each,  Staminate  and  Pistillate 


Fifty  staminate 
plants,  ounces 

Fifty  pistillate 
plants,  ounces 

37 
104 
266 
203 

Second  period,  ten  days 

68 

Third  period,  ten  days          ... 

164 
154 

Fourth  period,  ten  days 

Total  for  season 

610 

407 

This  shows  a  gain  of  the  staminate  plants  over  the  pistillate 
plants  of  about  50  per  cent,  for  the  whole  season,  the  greatest 
difference  being  in  the  first  period.  Hence,  it  seems  to  show 
that  staminate  plants  are  earlier  and  more  productive  than 
pistillate  ones.  Fruit  production  makes  a  greater  demand 
for  food  than  does  the  formation  of  stamens.  It  is  for  this 
reason  that  staminate  plants  are  able  to  produce  a  greater 
growth  of  "spears"  than  pistillate  ones. 

Pollination. — Common  asparagus  is  insect-pollinated. 
The  nectaries  are  small  and  concealed  at  the  base  of  the 
perianth.     Staminate  flowers  are  first  to  open. 


250  BOTANY  OF  CROP  PLANTS 

Fruit. — This  is  a  red,  spherical  berry  (Fig.  98)  with  three 
cells,  each  of  which  usually  contains  two  seeds.  The  perianth 
is  persistent  in  the  fruit.  The  dark,  somewhat  triangular 
seeds  run  about  fifty  to  a  gram.  They  preserve  their  germi- 
nating power  for  four  or  five  years,  and  may  even  retain  their 
vitality  when  soaked  in  water  for  a  year.  When  two  years 
old,  the  plant  begins  to  produce  seed,  but  the  best  seed  is  not 
produced -until  the  plant  is  three  or  four  years  old.  It  is  held 
that  the  best  seed  comes  from  the  lower  branches  of  the  plant. 

Geographical. — Common  asparagus  grows  wild  in  Europe 
and  Asia  and  has  escaped  from  cultivation  in  this  country, 
often  occurring  as  a  weed  in  fields  and  along  roadsides.  The 
plant  has  been  under  cultivation  for  over  2,000  years.  It  is 
cultivated  under  a  wide  range  of  temperature  conditions. 
Although  able  to  withstand  drought,  it  will  not  endure  an 
extremely  wet  soil. 

Types  and  Varieties. — Two  sorts  of  asparagus  are  sold  on 
the  market,  blanched  asparagus  and  green  asparagus. 
Green  asparagus  has  a  more  delicate  flavor  and  is  quite  gener- 
ally considered  the  more  desirable.  Blanched  asparagus  has 
a  much  thicker  stalk  than  the  green  sort.  It  must  be  under- 
stood that  these  two  market  types  of  asparagus  are  simply 
the  result  of  cultural  methods,  and  may  be  produced  from 
the  same  variety.  To  produce  etiolated  or  blanched  aspara- 
gus, the  plants  are  banked  or  ridged  up  with  soil  just  as  they 
appear  above  ground,  so  that  they  must  make  an  additional 
growth  of  4  to  10  inches  before  they  come  to  light.  The 
shoots  that  develop  in  the  soil  are,  of  course,  whitish  for  the 
reason  that  the  green  coloring  matter  (chlorophyll)  does  not 
form  in  the  absence  of  light. 

The  number  of  American  varieties  of  asparagus  is  small. 
The  most  common  of  these  are  Conover's  Colossal,'  Palmetto, 
Barr's  Mammoth,  Eclipse  and  Columbian  Mammoth  White. 


LILIACE^  251 

The  Palmetto  is  grown  most  in  the  south,  and  is  well-known 
on  account  of  its  resistance  to  asparagus  rust  {Puccinia 
aspardgi) . 

Uses. — The  common  asparagus  is  used  as  a  vegetable. 
As  a  rule  the  tender  shoots  are  eaten  fresh,  but  large  quan- 
tities are  also  canned  each  year.  The  principal  canning 
factories  are  located  in  CaHfornia  and  on  Long  Island,  New 
York.  For  canning,  Conover's  Colossal  and  Palmetto  have 
given  the  best  satisfaction.  A  method  has  been  devised  by 
which  the  soft  pulp  of  the  asparagus  plant  is  separated  from 
the  fiber  and  canned  in  the  form  of  a  thick  paste.  In 
European  countries,  particularly,  asparagus  is  dried.  In 
this  form  it  keeps  indefinitely. 

References 

Bailey,  L.  H.:  Preliminary  Synopsis  of  Onions  and  Some  of  Their  Allies. 

Rep.  of  Prof,  of  Hort.  and  Landsc.  Card.,  26th  Ann.  Rept.  State  Bd. 

Agr.  Mich.,  94-98,  1887. 
GoFF,  E.  S.:  Onion.     6th  Ann.  Rept.  N.  Y.  State  Agr.  Exp.  Sta.,  190-214, 

1887. 
Green,  W.  J.:  Asparagus.     Ohio  Agr.  Exp.  Sta.  Bull.  9  vol.  3  (second  series), 

241:  244,  1890. 
Gross,  A.  R  :  American  Onions.     Proc.  Soc.  Prom.  Agr.  Sci.,  1 15-132,  1901 


CHAPTER  XXI 
HORACE-®  (Mulberry  Family) 

The  mulberry  family  has  about  925  species  in  55  genera, 
occurring  in  tropical  and  temperate  regions  of  both  hemi- 
spheres. It  possesses  a  number  of  plants  of  considerable 
economic  importance.  Several  Asiatic  species  of  the  genus 
Ficus  yield  a  sap  from  which  rubber  is  made.  Ficus  carica 
is  our  cultivated  fig.  The  India  rubber  plant  of  green- 
houses and  in  home?,  is  Ficus  elastica.  Artocarpus  communis 
is  the  well-known  bread-fruit  of  the  tropics.  Toxylon 
pomijerum  is  the  osage  orange,  a  tree  whose  wood  is  valuable 
for  wheels,  posts  and  other  small  articles;  it  is  also  planted 
for  ornament.  The  paper  mulberry  {Papyrus  papyrifera) , 
is  a  native  of  Asia.  Its  bark  is  of  value  in  paper-making. 
Other  genera  of  importance  are  Morus  (mulberry),  Humulus 
(hop),  and  Cannabis  (hemp). 

Description. — Members  of  this  family  are  trees,  shrubs, 
or  herbs  with  a  milky  sap.  The  buds  may  be  naked  or  scaly. 
The  leaves  are  petioled  (stalked),  stipule-bearing,  and  borne 
oppositely  or  alternately  on  the  stem.  The  flowers  are  in 
ament-hke  spikes  or  heads  on  stalks  which  arise  in  the  axils 
of  leaves.  An  ament  is  a  spike-like  inflorescence  each  flower 
of  which  is  subtended  by  a  conspicuous  bract.  The  flowers 
may  be  monoecious  or  dioecious.  In  the  staminate  flower, 
the  calyx  is  three-  to  six-lobed  or  parted,  the  petals  are 
absent,  and  the  stamens  are  one  to  four,  inserted  at  the  base 
of  the  calyx.  The  filaments  are  thread-hke,  and  erect  or 
inflexed  in  the  bud.  In  the  pistillate  flower ,  the  calyx  consists 
252 


HORACES  253 

of  three  to  five  partly  united  sepals.  The  single  superior 
ovary  is  one-  to  two-celled  and  bears  one  to  two  styles. 
The  fruit  is  drupe-like  in  mulberries,  an  achene  in  hops  and 
hemp,  and  a  synconium  in  figs. 

Key  to  Principal  Genera 

Trees  or  shrubs. 

Flowers  not  in  a  receptacle;  buds  scaly,  Morus  (mulberry). 

Flowers  inside  of  a  hollow  receptacle;  buds  naked,  Fictis  (fig). 
Herbs. 

Erect  herbs,  Cannabis  (hemp). 

Twining  herbs,  Hiimuliis  (hop). 

MORUS  (Mulberry) 

Habit,  Stems. — Mulberries  are  trees  or  shrubs  with  milky 
sap  and  scaly  bark.  The  branches  are  slender  and  cylindrical. 
The  winter  buds  are  scaly. 

Leaves. — The  leaves  are  conduplicate  (Fig.  loi)  in  the  bud, 
alternate,  serrate,  three-nerved,  often  deeply  lobed,  and 
deciduous.     The  stipules  fall  soon  after  development.     The 


convolute  plicaie     conduplicate 

Fig.   ioi. — Three  principal  types  of  vernation. 

leaves  on  one  shoot  may  be  relatively  entire,  while  those  on 
another  may  be  moderately  or  deeply  and  irregularly  lobed. 
Inflorescences. — The  flowers  appear  rather  early  in  the 
season  in  the  axils  of  the  lower  leaves.  The  staminate  and 
pistillate  inflorescences  may  be  on  different  branches  of  the 
same  tree  (monoecious)  or  on  different  trees  (dioecious). 


254  BOTANY  OF  CROP  PLANTS 

The  staminate  inflorescences  are  long,  cylindrical  catkins. 
They  soon  fall.  The  calyx  of  the  staminate  flowers  is  deeply 
divided  into  four  rounded  lobes.  The  three  or  four  stamens 
are  inserted  at  the  base  of  the  calyx,  beneath  the  rudimentary 
pistil.  The  filaments  are  thread-like,  inflexed  in  the  bud 
and  uncoil  like  a  spring  at  the  moment  of  anther  dehiscence. 
The  two-celled  anthers  open  lengthwise  and  shed  their 
pollen  toward  the  inside  of  the  flower  (introrse  dehiscence). 

The  pistillate  inflorescences  are  short,  dense  catkins.  The 
flowers  in  these  have  a  deeply  four-lobed  calyx,  the  two  outer 
lobes  being  the  broader.  All  the  calyx  lobes  are  persistent, 
become  fleshy,  and  enclose  the  ovary  in  the  fruit.  The 
sessile  ovary  possesses  one  cell,  and  a  single  style  divided 
almost  to  the  base  into  two  very  slender,  hairy  stigmas. 

Fruit. — Each  ovary  develops  into  a  nutlet  bearing  rem- 
nants of  the  styles  at  the  tip  and  enclosed  by  the  thickened, 
juicy  calyx  lobes.  There  is  a  single  seed  within  each  fruit. 
However,  the  mulberry  "fruit"  as  commonly  understood, 
is  not  a  single  drupe-Uke  structure,  as  given  above,  but  an 
aggregate  of  these,  i.e.,  an  entire  pistillate  flower  cluster. 
The  single  fruits  are  very  much  crowded  together,  making  up 
a  collection,  which  commonly  goes  by  the  name  "mulberry." 

Other  "Mulberries." — The  so-called  paper  mulberry 
(Papyrus  papyrif era),  Sinsitiyeoi  eastern  Asia  and  now  planted 
for  ornament  in  many  parts  of  eastern  and  southern  United 
States,  may  be  easily  distinguished  from  the  true  mulberries 
(Morus)  by  its  non-edible  globular  fruit  and  the  occurrence 
of  its  pistillate  flowers  in  heads.  In  some  sections  of  the 
country,  the  "flowering  raspberry"  {Rubus  odoratus)  is 
confused  with  and  often  called  a  "mulberry."  It  is  true  that 
the  fruit  of  this  has  some  resemblance  to  a  mulberry  "fruit," 
but  instead  of  bearing  its  single  drupe-like  fruits  along  an 
axis,  the  true  drupes  of  the  raspberry  are  borne  on  a  receptacle. 


MORACEiE  255 

The  "fruit"  of  the  mulberry  is  a  collection  of  one-seeded 
fruits  developed  from  a  number  of  separate  flowers  in  a  dense 
inflorescence,  while  the  raspberry  "fruit"  represents  the 
matured  ovaries  of  a  number  of  pistils  belonging  to  a  single 
flower. 

Geographical. — The  genus  Moms  is  a  native  of  eastern  North  America, 
higher  altitudes  in  Mexico,  Central  America,  "Western  South  America,  Asia, 
Japan,  and  the  Indian  Archipelago. 

Key  to  Principal  Species  of  Genus  Morus 

Leaves  smooth  beneath,  sometimes  slightly  hairy  on  the  veins. 

Fruit  white  or  pinkish;  leaves  becoming  light  green  above.  Morns  alba 

(white  mulberry). 
Fruit  black;  leaves  becoming  dark  green  and  shining  above,  Morus  nigra 
(black  mulberry). 
Leaves  hairy  beneath;  fruit  red  or  purplish,  Morus  rubra  (red  mulberry), 

MORUS  ALBA  (White  Mulberry) 

Description. — This  is  a  low-branched  tree,  sometimes 
reaching  a  diameter  of  2  feet.  The  slender,  round  twigs  are 
at  first  hairy,  later  becoming  light  grayish  brown.  The  leaves 
are  light  green,  with  prominent  whitish  veins,  and  variously 
lobed  or  divided.  The  staminate  inflorescences  are  i  to  2 
centimeters  long,  slender  and  drooping.  The  pistillate  ones 
are  from  ^  to  i  centimeter  long.  The  fruit  is  white  or  pinkish 
in  color,  i  to  2  centimeters  long,  and  poor  in  quality. 

Geographical. — The  white  mulberry  is  a  native  of  Asia,  probably  of  China. 
It  has  spread  throughout  Europe  and  has  also  become  naturalized  in  eastern 
United  States. 

Types  and  Varieties. — ^Economic  Importance. — There  are 
a  number  of  types  and  varieties  of  the  white .  mulberry. 
According  to  L.  H.  Bailey,  the  following  are  forms  or  off- 
shoots of  Morus  alba:  Morus  alba  var.  tartarica  (Russian  mul- 
berry) and  Morus  alba  var.  venosa.     The  Russian  mulberry 


256  BOTANY   OF   CROP  PLANTS 

is  a  very  hardy,  low,  bushy  tree  with  small  fruit  which  varies 
in  color  from  white  to  red  and  almost  black.  It  is  an  im- 
portant wind-break  and  shelter-belt  tree  in  the  Great  Plains. 
Teas'  weeping  mulberry  is  an  ornamental  variety  of  the 
Russian.  Morus  alba  var.  venosa  (M.  nervosa)  is  an  orna- 
mental curiosity  bearing  jagged  leaves  with  white,  prominent 
veins. 

Morus  muUicaulis  {M.  alba  var.  muUicaulis)  was  intro- 
duced into  America  in  1826  and,  for  a  while,  gave  a  great 
impetus  to  the  attempts  to  grow  silkworms.  It  is  a  small 
tree  with  rough,  long-pointed  leaves. 

The  chief  horticultural  varieties  of  the  white  mulberry  are : 
New  American,  Trowbridge,  Thorburn  and  Downing.  The 
Downing  is  supposed  to  be  a  variety  of  M.  muUicaulis. 
However,  the  so-called  Downing  of  most  nurserymen  is  the 
New  American. 

Early  Attempts  in  the  United  States  to  Grow  Silk.— The 
white  mulberry  has  been  cultivated  from  the  earhest  times, 
chiefly  for  feeding  the  silkworm.  In  1621,  mulberries  were 
introduced  into  Virginia  by  the  London  Company  with  a  view 
of  establishing  the  silk  industry  in  the  New  World.  Early 
attempts  to  grow  silk  were  made  not  only  in  Virginia  but  in 
Carolina,  Georgia  and  Connecticut.  After  the  Revolution, 
early  in  the  19th  century,  silk  culture  was  again  agitated. 
There  existed  what  has  been  called  "  The  Morus  muUicaulis 
mania."  This  species  was  introduced  into  America  in  1826, 
and  since  it  was  thought  to  be  the  source  of  the  renowned 
Chinese  silk,  soon  gained  wide  fame  here.  The  "craze" 
died  down  in  about  1836,  and  since  that  time,  there  has  been 
little  effort  to  grow  silk  in  North  America  upon  a  commercial 
scale. 

Uses. — ^As  has  been  said,  the  white  mulberry  is  the  one 
upon  which  silkworms  are  raised.     In  the  Old  World  the 


HORACES  257 

wood  of  the  white  mulberry  is  used  for  various  purposes. 
The  roots  furnish  a  yellow  dyestuff.  In  western  Asia  the 
fruit  is  ground  into  a  meal  for  food. 

MORUS  NIGRA  (Black  Mulberry) 

Description. — The  black  mulberry  often  attains  a  height  of 
40  to  60  feet  and  a  diameter  of  i  to  2  feet.  The  numerous 
branches  are  slender,  slightly  hairy  at  first,  but  later  become 
smooth  and  brownish  gray.  The  leaves  are  dark,  dull  green, 
large,  pointed  at  the  apex,  rounded  or  heart-shaped  at  the 
base,  and  the  teeth  rather  small  and  close  together.  The 
st?imma,te  inflorescences  are  i  to  2  centimeters  long.  The  pis- 
tillate inflorescences  are  from  5  to  8  millimeters  long.  The 
fruit  is  black,  i  to  2  centimeters  long  and  has  a  deep  red  juice. 

Geographical. — Morus  nigra  is  a  native  of  Asia,  probably  of  Persia.  It 
has  become  naturalized  in  various  parts  of  Europe  and  in  the  United  States. 
In  this  country,  it  occurs  in  the  Southern  States  and  on  the!*Pacific  Coast. 

Varieties. — The  black  mulberry  has  always  been  the  prin- 
cipal fruit-bearing  mulberry  in  Europe  and,  in  an  early  day, 
in  America,  but  it  is  less  tender  than  our  native  red 
mulberry  {Morus  rubra),  and  hence  has  been  replaced  by. 
the  latter,  especially  in  the  north.  The  Black  Persian 
variety  of  the  Southern  States  and  California  belongs  to 
this  species. 

Uses. — Over  central  and  eastern  Asia  the  black  mulberry 
is  a  common  and  rather  valuable  fruit,  and  large  quantities 
are  dried.  The  wood  is  used  like  that  of  the  white  mulberry. 
The  juice  of  the  ripe  fruit  has  medicinal  value.  The  fruit  of 
all  mulberries  is  relished  by  hogs  and  poultry,  and  it  is  the 
practice  in  some  localities  to  plant  mulberry  trees  along 
fences  enclosing  pastures  or  poultry  yards. 
17 


258  BOTANY   OF   CROP   PLANTS  ' 

MORUS  RUBRA  (Red  Mulberry) 

Description. — This  is  the  largest  of  the  mulberry  trees, 
reaching  a  height  of  60  feet  and  a  diameter  of  5  to  7  feet. 
The  twigs  are  slender,  dark  green,  with  a  reddish  tinge,  but 
finally  become  dark  brown.  The  leaves  are  large,  those  on 
young  shoots  deeply  lobed,  and  with  oblique  and  rounded 
sinuses,  in  the  bases  of  which  there  are  no  teeth;  they  are 
rounded  or  heart-shaped  at  the  base,  singly  or  doubly  toothed 
or  three-lobed,  and  with  a  rough  upper  surface  and  a  soft 
lower  surface.  The  staminate  inflorescences  are  slender  and 
cylindric.  The  pistillate  inflorescences  are  much  shorter  than 
the  staminate  ones.  The  fruit  is  bright  red,  becoming  nearly 
black,  sweet  and  juicy,  and  about  i  centimeter  long. 

Geographical. — The  red  mulberry  is  a  native  of  North  America.  It 
grows  from  Massachusetts  to  southern  Ontario,  Michigan,  and  southeastern 
Nebraska,  eastern  Kansas  and  southward  to  Florida  and  Texas.  It  is  most 
abundant  and  reaches  its  largest  size  in  the  Central  States. 

Varieties  and  Uses. — There  are  a  number  of  varieties  of 
the  red  mulberry,  all  of  which  are  more  hardy  than  those  of 
the  black  mulberry.  The  principal  horticultural  varieties 
are  Hicks,  Johnson  and  Stubbs.  The  wood  is  used  for  posts 
and  fencing,  but  finds  its  greatest  usefulness  in  the  making  of 
shoe  lasts,  churns  and  cooperage  material. 

HUMULUS  (Hop) 
HUMULUS  LUPULUS  (Common  Hop) 

Root. — The  root  system  of  the  common  hop  plant  is  large 
as  compared  with  above  ground  parts.  This  holds  true  in 
both  young  and  old  plants.  The  roots  extend  to  consider- 
able depths  in  the  soil. and  also  spread.horizontally  in  the  sur- 
face layers.  They  give  rise  to  a  fine  network  of  small  rootlets. 
Older  roots  become  covered  with  a  reddish-brown  bark. 


MORACE^ 


259 


Stems. — The  common  hop  is  a  perennial,  herbaceous, 
climbing  plant  from  an  underground  stem,  a  rootstock. 
These  rootstocks  may  become  quite  woody.  They  are 
commonly  used  for  propagation. 
Cuttings  from  them  readily  form 
numerous  adventitious  roots. 
Hop  plants  send  out,  near  the 
ground  line,  "runners"  which 
extend  several  feet.  These  are 
cut  into  pieces,  possessing  two  or 
more  buds,  and  used  for  propaga- 
tion. They  are  known  in  hop 
culture  as  "roots."  However, 
they  are  stems  and  not  true  roots. 

The  aerial  stems,  commonly 
known  as  "bines,"  die  back  to  the 
ground  in  the  fall.  The  lower 
portion  of  each  stalk  ("bine"), 
below  ground,  does  not  die,  but 
forms  an  addition  to  the  root- 
stock.  The  above  ground  stems 
are  herbaceous,  hollow  and  angu- 
lar, and  vary  in  color  from  pale 
green  to  purplish  red  or  green 
streaked  with  purple.  They  have 
a  twining  habit,  always  winding 
about  the  support  clockwise  (Fig. 
102) .  The  angle  of  the  support  de- 
termines, to  a  degree,  the  manner 

and  rate  of  growth.  The  most  rapid  and  uniform  growth  is 
made,  and  the  longest  internodes  produced,  when  the  sup- 
ports are. vertical,  The  "bines"  are  assisted  in  their  climb- 
ing and  clinging  to  supports  by  the  presence  of  hooked,  re- 


FlG. 


[02. — Dextrorse  twining 
of  hop  stem. 


26o  BOTANY   OF   CROP   PLANTS 

trorse  hairs  on  each  of  the  six  edges  of  the  stems,  and  on  the 
petioles  and  leaf  veins.  The  main  stems  bear  opposite 
lateral  branches.  These  reach  their  greatest  length  near  the 
middle  of  the  main  stem.  They  bear  the  pistillate  inflores- 
cences (hops),  and  hence  it  is  important  that  they  be  formed 
in  abundance. 

Leaves. — The  hop  leaves  are  opposite,  broad,  palmately 
veined,  and  three-  to  five-toothed  (Fig.  103).  In  palmately 
veined  leaves  there  are  several  main  veins  which  radiate 
from  the  leaf  base.  The  stipules  are  broad,  those  of  opposite 
leaves  being  united. 

Inflorescences. — Hops  are  commonly  dioecious,  rarely 
monoecious.  Hermaphroditism  in  hops  has  been  noted. 
Some  have  held  that  injury  is  the  cause  of  this  abnormality. 
This  theory  has  been  refuted  by  Stockberger  as  a  result  of  a 
number  of  experiments  in  which  the  plants  were  cut  back, 
or  pruned,  or  the  tap  root  removed  or  portions  of  the  crown 
removed.  All  of  them  failed  to  develop  the  abnormality 
(hermaphroditism).  Hop  plants  of  this  type  arise  independ- 
ently of  injury.  They  transmit  the  abnormality  to  their 
progeny  when  propagated  vegetatively.  It  is  held  that 
perfect  flowers  appear  only  in  pistillate  inflorescences. 

S laminate  inflorescences  (Fig.  103,  B)  are  paniculate,  and 
grow  from  the  axils  of  the  main  shoot  or  from  the  axils  of 
lateral  ones.  Pistillate  inflorescences  (Fig.  103,  A)  are  spike- 
like in  appearance.  They  are  the  "hops"  of  commerce  and 
are  often  spoken  of  as  "burrs"  or  "strobiles."  These  are 
mostly  borne  on  lateral  branches  from  the  main  stem ;  they 
arise  in  the  axils  of  the  leaves. 

The  pistillate  inflorescence  has  a  central,  hairy  axis  (Fig. 
103,  C)  upon  which  are  arranged  a  number  of  very  short 
lateral  branches  or  axes.  At  the  base  of  each  short  lateral 
branch,  or  axis,  is  a  pair  of  bract-like  structures.     These  are  in 


MORACEiE 


261 


_  Fig.  1 03 .—Hop  (Humulus  lupulus) .  A ,  portion  of  plant  showing  pistillate 
inflorescences;  B.  staminate  inflorescence;  C,  rachis  of  pistillate  inflorescence 
("hop"). 


262 


BOTANY   OF   CROP   PLANTS 


reality  stipules  belonging  to  leaves  which,  normally,  do 
not  develop.  Each  of  the  lateral  branches  bears  four  pis- 
tillate flowers.  Below  each  flower  is  a  single  bracteole 
(small  bract).  Hence,  examination  of  a  single  lateral  axis 
or  branch  shows  it  to  be  made  up  of  the  following  parts, 
from  below  upwards:  (i)  two  bract-like  stipules;  (2)  brac- 


—  bract-Jike 

stipule 

^bracteole 


Fig.   104. — Hop   (Humulus  lupvdus).     A,   single  staminate  flower;  B,   two 
pistillate  flowers  with  bracteoles  and  bract-like  stipule.     (B  after  Wossidlo.) 


teole  and  first  flower;  (3)  bracteole  and  second  flower;  (4) 
bracteole  and  third  flower;  (5)  bracteole  and  fourth  flower. 
Flowers. — The  staminate  flowers  (Fig.  104,  A)  measure 
about  6  millimeters  in  diameter.  They  have  a  five-parted 
calyx,  no  corolla,  and  five  stamens  opposite  the  calyx  lobes. 
Each  pistillate  flower  (Fig.  104,  B)  is  subtended  by  a  single 
bracteole  (Fig.  105,  A)  that  partially  encloses  it  at  maturity. 
It  has  a  single  ovary  surrounded  by  a  cup-shaped  perianth. 
There  is  one  style  with  two  long  stigmas,  which  are  covered 
their  full  length  with  papillae 


HORACES  263 

Pollination,  Fertilization,  and  Development  of  the 
"Hops." — The  long,  brush-like  stigmas  adapt  the  plant 
to  wind  pollination.  When  the  pistillate  inflorescences 
are  young,  the  stigmas  protrude  from  between  the  small 
"bracts"  and  become  very  conspicuous.  Only  the  basal 
bracts  of  the  inflorescence  are  to  be  seen.  As  soon  as 
fertilization  has  taken  place  the  stigmas  ("brush")  drop 
off  and  the  "bracts"  rapidly  increase  in  size.     ' 

The  necessity  for  fertilization  to  secure  the  best  develop- 
ment of  the  "hop"  has  been  determined  by  a  number  of 
observers.  The  hops  will  only  develop  properly  when 
a  certain  number  of  bracteoles  bear  seeds.'  If  the  young 
pistillate  inflorescences  ("burrs")  are  enclosed  in  paper  bags 
to  prevent  fertiKzation,  no  seeds  result,  and  the  hops  are 
poorly  developed.  It  is  true  that  the  bracteoles  develop 
to  some  extent  without  fertilization  of  the  ovules,  but  the 
bracteoles  connected  with  normal  seeds  are.  mucB' larger  and 
a  brighter  yellow  than  those  bearing  rudimentary  Seeds. 
Furthermore,  hops,  not  fertilized,  remain  in  blossom  longer 
than  those  fertilized.  Howard  has  shown  that  hops  arti- 
ficially pollinated  start  to  grow  out  at  once,  while  those  not 
pollinated  at  all  begin  their  growth  seven  to  ten  days  later. 
He  shows  that  fertilization  stimulates  growth,  hastens 
ripening,  improves  the  color  and  increases  the  mold-resisting 
power  of  the  plant.  Salmon  and  Amos  have  shown  that,  in 
England  at  least,  seeded  hops  bearing  an  average  of  9.5 
seeds  per  hop,  contained  15  per  cent,  resin  and  produced 
147  pounds  of  resin  per  acre,  while  seedless  hops  contained 
17.2  per  cent,  of  resin  and  produced  92  pounds  of  resin 
per  acre.  It  is  true  that  there  are  certain  disadvantages 
connected  with  growing  seeded  hops.  Extra  space  is  needed 
for  growing  staminate  plants,  and  there  is  also  a  possi- 


264 


BOTANY   OF   CROP   PLANTS 


brac\eo\e 


bility  that  the  soil   is  more  quickly  exhausted  by   seeded 
hops  than  by  seedless  ones. 

The  Mature  Fruit. — The  fruit  (Fig.  105)  is  a  small  achene 
surrounded  by   the  persistent  cup-shaped  perianth.     The 
single  seed  within  has  a  curved 
embryo  about  which  is  a  small 
amount  of  endosperm. 

Lupulin  Glands. — In  the  ma- 
ture hop,  the  outer  surface  of 
the  bracteoles,  the  perianth, 
and,  to  a  less  extent,  the  bases 
of  the  bract-Hke  stipules  are 
covered  with  yellow  pollen-like 
grains,  the  so-called  "  hop-meal " 
or  "lupuHn"  (Fig.  105). 

Each  yellow  grain  is  a  cup- 
shaped,  multicellular,  glandular 
hair  filled  with  a  resinous  secre- 
tion. It  is  an  outgrowth  of  an 
epidermal  cell  and  consists  of  a 
short  stalk  and  a  cup  of  one 
layer  of  cells.  Each  cell  has  a 
rather  thick  cuticle.  The  secre- 
tion of  the  cells  collects  just 
beneath  the  cuticle,  raising  the 
latter  up  until  finally  the  cup-shaped  depression  is  filled 
with  the  secretion  which  remains  covered  by  the  cuticle  itself. 
In  immature  hops,  the  lupulin  glands  are  bright  yellow  and 
transparent.  In  mature  hops,  they  are  a  paler  yellow  and 
somewhat  opaque.  The  commercial  value  of  hops  depends 
entirely  upon  the  amount  and  quality  of  the  "hop-meal." 
It  constitutes  from  15  to  32  per  cent,  by  weight  of  the  hop. 
Geographical. — The    hop    grows  wild    in    England,   the 


Fig.  105. — Hop  (Humulus  lupu- 
lus).  A,  bracteole;  B,  immature 
lupulin  gland;  C,  same  in  section; 
D,  mature  lupulin  gland;  E,  same 
in  section.     (B-E  after  Percival.) 


MORACEiE  265 

northern  part  of  the  continent  of  Europe  and  in  Asia  as  far  as 
eastern  Siberia  and  south  to  Persia;  it  also  grows  wild  in 
North  America,  across  the  continent  westward  to  New 
Mexico  and  British  America.  It  requires  a  moist,  cool  ch- 
mate  to  attain  its  best  development.  Oregon,  California, 
New  York,  and  Washington  are  the  leading  States  in  the 
commercial  production  of  hops. 

Closely  Related  Species. — Humulus  japonicus,  the  Japa- 
nese hop,  is  grown  as  an  ornamental  plant.  It  is  an  annual ; 
its  pistillate  inflorescence  does  not  enlarge  into  a  "hop." 
Along  streams  from  Wyoming  to  Utah,  New  Mexico  and 
Arizona,  there  is  a  hop  (Humulus  lupulus  neomexicanus) 
which  is  distinguished  from  the  Linnaean  species  by  its  more 
deeply  divided  leaves  and  more  sharply  acuminate  bracts. 

Varieties. — There  are  a  number  of  varieties  of  hops,  based 
upon  length  and  color  of  vines,  size,  shape  and  color  of  hop, 
shape  of  bracteoles  and  stipular  bracts,  aroma,  lupulin  con- 
tent and  time  of  ripening.  In  Cahfornia  the  chief  variety  is 
Large  Gray  American.  Common  New  York  varieties  are 
Enghsh  Cluster,  Pompey,  Humphrey  Seedling  and  Canada. 

Composition. — The  composition  of  the  strobiles  or  hops  is 
of  great  importance,  for  they  possess  the  valuable  constitu- 
ents of  the  plant,  most  of  which  reside  in  the  lupulin  glands. 
There  are  four  principal  active  ingredients  in  the  "lupuUn," 
as  follows: 

1.  Essential  oil. 

2.  Non-resinous  bitter  principle. 

3.  Resins. 

4.  Tannin. 

Hop  oil  is  volatile  and  gives  the  hop  its  characteristic 
aroma.  The  amount  of  essential  oil  in  hops  varies  from  0.2 
to  0.8  per  cent.     The  non-resinous  bitter  principle  of  the  hop 


266  BOTANY  OF  CROP  PLANTS 

hop  is  probably  the  alkaloid,  lupuline.  Of  the  r  esins  in  the 
lupulin  glands,  two  principal  ones  have  been  identified,  a  hard 
and  a  soft  resin.  The  hard  resin  has  a  slight  bitter  taste  and 
little  or  no  antiseptic  power  in  the  beer  wort.  The  soft 
resins  are  much  more  bitter,  imparting  this  taste  to  the  beer 
wort;  they  also'prevent  the  growth  of  bacteria  in  the  wort 
and  thus  have  a  preservative  effect.  The  total  resin  content 
of  hops  varies  from  lo  to  i8  per  cent.  Hop  tannin  makes 
up  about  4  to  5  per  cent,  of  the  hop.  It  is  thought  by  some 
that  it  serves  to  precipitate  the  albuminous  material  from 
beer  wort. 

Uses  of  Hops. — In  some  European  locaHties,  young  hop 
sprouts  are  used  as  an  early  spring  vegetable.  The  most 
tender  sprouts  are  those  which  have  been  covered  with  soil 
during  the  winter. 

Before  the  days  of  yeast  cakes,  yeast  for  bread-making  was 
made  by  cultivating  wild  yeast  in  a  decoction  of  hops  and 
water.  Some  of  the  material  obtained  was  mixed  with  the 
dough.  The  various  constituents  extracted  from  the  hops 
add  flavor  to  the  bread,  and  also  have  antiseptic  properties. 

The  most  important  use  of  hops,  however,  is  in  the  brewing 
process.  Preparatory  to  their  use  in  the  breweries,  the  hops 
are  taken  through  a  curing  process  in  which  they  are  kiln- 
dried,  and  then  subjected  to  the  fumes  of  burning  sulphur. 
''Sulphuring"  bleaches  the  hops,  and  acts  as  a  preservative. 
After  the  sweet  beer  wort  is  made  in  the  brewing  process,  it 
is  boiled  with  hops.  In  this  process,  among  other  effects, 
the  flavor  of  the  wort  is  improved  by  the  extraction  of  the 
active  ingredients  in  the  hops.  The  essential  oil  of  the  lupu- 
Hn  glands  imparts  an  aroma  to  the  beer,  the  non-resinous 
bitter  principle  and  the  resins  give  to  the  hopped  wort  a  shghtly 
bitter  taste,  and  the  tannin  probably  serves  to  precipitate 
albuminous   substances.     Moreover,    the   maHc   and   citric 


MORACE.E  267 

acids  in  the  hops  tend  to  increase  the  acidity  of  the  wort,  and 
the  ash  adds  to  its  mineral  composition. 

FICUS  (Fig) 

Habit,  Roots,  Stems. — Members  of  this  genus  are  trees, 
shrubs  or  woody  cHmbers  (Hanas) .  A  number  of  species  are 
parasitic  on  other  trees.  A  parasite  is  an  organism  which 
secures  its  food  material  from  another  living  organism.  A 
complete  parasite  has  no  power  of  making  its  own  food  as  do 
those  plants  which  possess  chlorophyll.  The  Golden  Fig 
{Ficus  aurea)  begins  life  as  an  epiphyte ;  the  seed  germinates 
in  the  crevices  of  other  trees;  the  aerial  roots  that  are  first 
produced  take  root  when  they  strike  the  soil,  and  hence  be- 
come trunk-like.  Aerial  roots  may  be  sent  down  from 
branches,  take  root  and  also  form  trunks.  The  banyan  tree 
(Ficus  henghalensis)  also  starts  its  Hfe  on  the  bough  of  a  tree, 
receiving  all  its  nutriment  from  substances  available  on  the 
bark.  Hence  in  its  early  life  the  banyan  is  an  epiphyte. 
When  once  rooted  in  the  soil,  the  plant  becomes  independent. 
In  the  East  Indies,  the  banyan  is  "universally  known  as  an 
immense  Kving  columned  hall,  consisting  of  a  flat  expanded 
canopy  of  leaves  and  numerous  stem-like  prop  roots  growing 
down  from  the  boughs"  (Schimper's  Plant  Geography). 

Leaves. — The  leaves  are  alternate,  sometimes  opposite, 
thick,  leathery  and  deciduous  or  persistent.  In  the 
Buddhists'  sacred  Peepul  tree  {Ficus  religiosa),  a  plant  of 
tropical  rain  forests,  the  leaves  have  a  long  "dripping  point," 
by  means  of  which  rain  water  is  soon  drained  off.  The 
stipules  are  interpetiolar  and  early  deciduous. 

Inflorescence. — The  flowers  occur  within  an  enlarged, 
fleshy,  hollow  receptacle  (Fig.  106)  which  is  commonly  borne 
in  the  axils  of  leaves.  Staminate  and  pistillate  flowers  may 
be  borne  in  the  same  receptacle  or  in  different  receptacles. 


268 


BOTANY   OF   CROP   PLANTS 


Some  tropical  figs  are  cauliflorus,  that  is,  the  receptacle 
with  its  numerous  small  flowers  is  borne  on  main  stems  or 
branches.  This  is  a  rather  unusual  condition ;  in  our  common 
woody  plants,  the  flowers  and  fruit  are  borne  on  young 
twigs  only. 

Staminate  flowers  have  a  two-  to  six-parted  perianth  (some- 
times none) ,  and  one  to  three  stamens  with  united  filaments. 
In  the  staminate  flowers,  there  is  no  indication  of  an  ovary. 


Fig.  io6. — Pollination  of  the  fig  (Ficus  carica).  A,  itnedium  lengthwise 
section  of  a  synconium  containing  fertile  pistillate  flowers;  note  the  female  fig 
wasp  near  the  orifice,  also  another  one  which  is  inside.  B,  similar  section  of 
synconium  showing  gall  flowers.     {After  Kerner.) 


Pistillate  flowers  have  a  two-  to  six-parted  perianth  (some- 
times none),  a  single  one-celled  ovary  and  single  style.  The 
small  nutlets  are  enclosed  in  the  thick,  succulent  receptacle, 
forming  a  fruit  known  as  a  synconium  ("fig")- 

Geographical  Distribution,  and  Economic  Importance. — 
There  are  about  600  species  of  the  genus  Ficus  very  widely 
distributed  throughout  the  American  tropics,  southern  Asia 
and  the  islands  of  the  Pacific.  Two  species,  F.  aurea  and  F. 
hrevijolia,  are  native  to  peninsular  Florida  and  the  Keys, 
while  F.  carica  has  been  introduced  into  southern  California 


MORACEiE  269 

and  a  number  of  the  Gulf  States.  As  compared  with  other 
genera  in  the  family  Moraceae,  Ficus  is  by  far  of  the  greatest 
economic  importance.  The  most  important  species  is  Ficus 
carica,  the  common  fig  of  commerce. 

FICUS  CARICA  (Common  Fig) 

Habit  of  Plant,  and  Stem. — The  common  fig  is  a  shrub  or 
small  tree,  seldom  reaching  a  height  of  more  than  25  feet. 
The  main  trunk  of  the  tree  is  short.  It  branches  rather 
irregularly,  forming  a  round  head.  The  gray  or  reddish  bark 
is  smooth  and  fits  closely  to  the  wood.  The  twigs  are  stout 
and  thick,  at  first  somewhat  hairy  but  later  becoming  smooth 
and  grayish-green  in  color.  The  fig  is  propagated  mainly 
from  stem  cuttings. 

Leaves. — These  are  thick  and  leathery  and  from  5  to  15 
centimeters  long.  The  general  outline  of  the  leaf  is  usually 
oval,  sometimes  about  circular.  The  leaf  base  is  truncate 
or  shghtly  heart-shaped.  There  are  five  to  seven  deep  lobes, 
which  are  coarsely  toothed  or  slightly  lobed  again;  each  lobe 
is  blunt  at  the  tip.  The  leaves  are  light  green,  rough  and 
hairy  on  the  upper  side,  paler  and  hairy  on  the  under  side; 
leaf  venation  is  prominent. 

Inflorescence,  and  Flowers. — The  numerous  small  flowers 
Hne  the  inner  wall  of  a  hollow  receptacle  (Fig.  106),  except 
near  the  small  opening  ("eye")  at  the  apex  where  there  are 
scales  or  small  leaves. 

Among  the  various  types  of  Ficus  carica,  there  are  four 
distinct  kinds  of  flowers,  staminate,  pistillate,  gall  and  mule. 

S laminate  Flowers  (Fig.  107,  E). — These  rarely  occur  in 
cultivated  figs,  being  found  for  the  most  part  in  the  wild 
fig  (Caprifig).  They  occur  just  below  the  scales  in  the 
receptacle.     Each  staminate  flower  usually  has  a  four-lobed 


270 


BOTANY   OF   CROP  PLANTS 


perianth  which  is  shorter  than  the  stamens.     The  stamens 
vary  from  one  to  five;  four  is  the  ordinary  number. 


nucellus 
e0^  cf  < 


Fig.  107. — Flowers  of  fig  (Ficus  carica).  A,  B  and  C,  mule  flowers;  D, 
long-styled  pistillate  flower;  E,  staminate  flower;  F,  gall  produced  from  a 
short-styled  gall  flower;  G,  fig  wasp  escaping  from  a  gall;  H,  gall  flower.  {A, 
B,  and  C  after  Eisen;  D  toG  after  Kerner;  H  after  Solms-Laubach.) 


Pistillate  Flowers  {Fig.  107,  D). — Pistillate  flowers  are  some- 
times found  in  the  Common  Mission  figs;  they  are  the  only 
sort  in  Smyrna  figs;  they  also  occur  in  the  second  crop  of  San 


HORACES  271 

Pedro  figs,  the  first  crop  of  Adriatic  fi_gs,  the  second  crop  of 
Erinocyce  figs  and  the  second  crop  (mammoni)  of  Caprifigs. 
In  the  receptacle  of  the  latter,  they  come  below  the  staminate 
flowers.  The  pistillate  flowers  have  a  three-  to  five-lobed 
perianth,  which  is  rather  fleshy.  The  single,  superior  ovary 
bears  a  bent  style  several  times  longer  than  the  ovary,  and 
often  divided  into  two  unequal  stigmatic  lobes. 

Gall  Flowers  (Fig.  107,  H). — These  are  found  only  in  Capri- 
figs and  Erinocyce  figs.  They  are  degenerate  or  transformed 
pistillate  flowers,  not  producing  seed;  the  ovary  harbors 
the  eggs  and  larvae  of  the  fig  wasp  (Blastophaga).  It  must 
not  be  thought  that  gall  flowers  are  true  pistillate  flowers 
modified  by  the  fig  wasp;  they  exist  independent  of  the  wasp; 
the  wasps  select  them  for  the  deposit  of  their  eggs.  Gall 
flowers^occur  at  the  base  of  the  receptacle.  Their  perianth 
is  smaller  than  that  in  true  pistillate  flowers;  the  style  is 
very  short  or  entirely  wanting;  the  embryo  is  imperfect  and 
the  stigmas  do  not  possess  receptive  papillae. 

Mule  Flowers  (Fig.  107,  A,  B,  C, ). — With  the'[exception  of 
an  occasional  pistillate  flower,  mule  flowers  are  the  only  kind 
found  in  the  common  edible  fig.  They  are  also  the  only 
sort  present  in  the  first  crop  of  San  Pedro  figs,  and  second 
crop  of  Adriatic  figs.  They  are  not  present  in  Caprifigs. 
They  are  imperfect  pistillate  flowers  neither  capable  of  matur- 
ing seed  nor  serving  as  a  breeding  place  for  the  fig  wasp. 
The  style  is  intermediate  in  length  between  that  of  gall  and 
of  true  pistillate  flowers;  the  stigmas  are  non-receptive;  the 
embryo  is  imperfect,  and  hence  no  seed  is  produced. 

Pollination. — The  common  edible  fig  comes  to  maturity 
without  pollination,  artificial  or  otherwise.  In  other  types 
of  figs  all  or  at  least  one  of  the  crops  require  the  visitation  of 
the  fig  wasp  {Blastophaga  grossorum)  in  order  that  the  fruit 
form  properly.     The  close  dependence  of  certain  figs  upon  this 


272  BOTANY  OF  CROP  PLANTS 

insect  has  been  a  topic  of  great  interest  to  students  of  botany. 
Pollination  in  the  Caprifig  will  be  considered  first. 

Crops  of  Fruit  inCaprifigs.— In  the  wild  fig  (Caprifig)  there 
are  three  crops  of  fruit  in  a  year.     These  are  as  follows: 

First  Crop  (Profichi). — The  figs  of  this  crop  form  in  the 
autumn,  rest  over  the  winter  and  mature  the  following 
June  or  July.  They  bear  staminate  and  gall  flowers  but 
no  pistillate  flowers.  When  the  figs  are  about  one-fourth 
grown,  female  wasps  enter  and  deposit  their  eggs  in  the 
gall  flowers.  In  about  two  months,  the  eggs  hatch  out,  the 
perfect  wasps  emerge  and  the  females,  covered  with  pollen, 
come  from  the  fig  and  seek  other  figs  in  which  to  deposit 
their  eggs.  By  this  time  (June  and  July)  the  second  crop 
of  figs  is  about  one-fourth  grown. 

Second  Crop  (Mammoni). — The  fruits  of  this  crop  possess 
staminate,  pistillate  and  gall  flowers.  The  wasps  which 
emerge  from  the  figs  of  the  first  crop  enter  the  narrow  orifice 
at  the  apex  of  the  receptacle  (second  crop) ,  crawl  down  along 
the  inner  side,  first  over  the  staminate  flowers,  then  over 
the  pistillate  flowers,  finally  reaching  the  gall  flowers  at  the 
base  of  the  receptacle,  in  which  they  deposit  the  eggs.  The 
pollen  on  their  bodies  is  rubbed  off  on  the  receptive  stigmas, 
which  are  elevated  on  the  long,  curved  styles,  and  thus  polli- 
nation is  secured.  As  a  result,  a  few  fully  developed  seeds  are 
found  in  the  second  crop  of  Caprifigs.  In  August  or  Sep- 
tember the  eggs,  deposited  in  the  gall  flowers  of  the  second 
crop,  hatch  out.  The  mature  female  wasps  emerge  from  the 
receptacle,  in  search  of  other  figs  in  which  to  lay  their 
eggs.  By  this  time  the  third  crop  of  Caprifigs  is  about  one- 
fourth  grown. 

Third  Crop  (Mamme). — The  figs  of  this  crop  possess 
staminate  and  gall,  but  no  female  flowers.  When  they 
are    about   one-fourth   growu     in   August    or    September, 


HORACES  273 

wasps  from  the  second  crop  come  to  them,  depositing  eggs 
in  the  gall  flowers.  These  figs,  together  with  the  eggs 
of  the  wasp,  hibernate  until  March  or  April,  when  the  per- 
fect insects  hatch  out,  seeking  the  profichi  stage. 
"^  Caprification. — It  will  be  recalled  that  the  com- 
mon edible  fig  matures  its  fruit  without  fertihzation. 
Such  is  not  the  case  with  some  other  types,  particularly 
Smyrna  figs.  The  latter  have  only  pistillate  flowers  and, 
unless  these  are  fertiUzed,  the  receptacle  does  not  come  to 
full  maturity.  Hence,  it  has  been  found  necessary,  in 
order  to  grow  Smyrna  figs,  to  resort  to  artificial  fertilization. 

The  artificial  process  of  fertihzation  as  applied  to  figs 
is  termed  caprification.  In  this  horticultural  process,  a 
number  of  first-crop  figs  (profichi)  of  the  Caprifig  are  sus- 
pended on  the  branches  of  the  Smyrna  tree.  The  female 
Blastophagas  which  hatch  from  the  eggs  in  the  gall  flowers 
of  the  profichi  become  covered  with  pollen  as  they  emerge 
from  the  figs.  In  search  of  a  place  to  lay  their  eggs,  they 
go  to  the  partly  mature  figs  of  Smyrna.  They  enter  the 
orifice  of  the  fig  and  scatter  pollen  on  the  stigmas,  and  fer- 
tilization of  the  ovules  ensues.  The  pistillate  flowers  of  the 
Smyrna  fig,  unlike  the  gall  flowers,  have  styles  of  such  a 
length  that  the  wasps  are  unable  to  lay  their  eggs  in  the 
proper  place.  Consequently,  the  wasps  perish  in  the 
fruit  and  their  bodies  are  absorbed  by  the  growing  cells. 
Gall  flowers  are  the  only  ones  in  which  eggs  may  be  laid  prop- 
erly, and  hatch. 

In  California,  caprification  of  Smyrna  figs  is  done  in 
June  or  July.  The  second  crop  of  San  Pedro  figs  and 
the  first  crop,  but  not  the  second,  of  Adriatic  figs,  require 
caprification. 

Effects  of  Fertilization  [caprification) .  In  caprifigs,  as  has 
been  noted,  there  are  two  general  types  of  receptacles:  those 


274  BOTANY  OF  CROP  PLANTS 

possessing  pistillate  flowers  (mammoni)  and  those  without 
pistillate  flowers  (profichi  and  mamme).  The  effects  of 
fertiUzation  may  be  observed  in  comparing  the  behavior 
of  caprificated  figs  of  the  mammoni  with  the  non-caprificated 
ones  of  the  profichi  and  mamme,  or  the  non-caprificated  ones 
of  the  mammoni. 

Prior  to  fertilization,  the  figs  of  the  two  types  are  about 
the  same  size.  Caprificated  figs  become  larger  than  those  not 
fertiHzed;  they  cling  to  the  tree  more  tightly,  the  ribs  are 
more  pronounced  and  the  branches  that  bear  them  grow 
more  vigorously. 

As  has  been  indicated,  Smyrna  figs  must  be  caprificated 
to  bring  about  the  development  of  the  ovaries  and  seeds  and 
the  proper  ripening  of  the  receptacle.  The  superiority  of 
Smyrna  figs  is  due  to  the  aromatic  flavor  of  the  seeds. 

The  Mature  Fruit.— The  "fruit"  of  fig  (Fig.  io6)  is  termed 
a  synconium.  This  is  a  pear-shaped  receptacle  on  a  very 
short  stalk;  the  nutlets  (true  fruits),  when  present,  are  im- 
bedded on  the  inside  of  the  fleshy  receptacle  walls.  At  the 
apex  of  the  fig,  is  the  "eye"  or  orifice  of  the  receptacle. 
The  "neck"  and  "cheeks"  (sides)  of  the  fruit  are  marked  by 
a  number  of  rings.  The  fruits  vary  widely  as  to  size,  form, 
neck,  stalk,  ribs,  eye,  color  of  skin,  color  of  pulp,  seeds, 
quality  and  growth. 

Geographical. — Ficus  carica  is  considered  to  be  a  native 
of  southern  Arabia.  Some  one  or  more  of  its  different  types 
are  now  grown  in  most  of  the  tropical  and  subtropical  coun- 
tries. The  first  figs  brought  into  the  United  States  were  a 
common  edible  type  and  were  introduced  into  CaHfornia  by 
the  Franciscan  order  of  Mission  Fathers.  From  CaHfornia, 
they  have  spread  and  are  now  being  cultivated  in  many  of 
the  Southern  States.  Fig  culture  in  the  cooler  sections  of  the 
United  States  is  very  limited,  and  special  care  needs  to  be 


MORACE^  275 

taken  there  to  prevent  the  trees  from  winter-killing;  this 
object  is  attained  by  growing  the  plant  in  a  bush  form  and 
covering  it  with  several  inches  of  soil  during  the  winter. 

Closely  Related  Species  in  the  United  States.  In  Florida, 
there  are  two  native  figs  {F.  aurea  and  F.  brevifolia)  which 
are  distinguished  from  the  common  figs  by  their  entire, 
smooth  leaves,  and  small,  inedible  fruit. 

Types  of  Figs. — Eisen  describes  the  following  types  of  figs : 

1.  Common  Figs  or  Mission  Figs. — These  produce  two 
crops  of  fruit  without  caprification  or  fertilization.  Mule 
and  a  few  pistillate  flowers  are  present,  but  there  are  no 
gall  or  staminate  flowers,  except  in  a  very  few  cases.  The 
figs  of  the  first  crop  occur  on  old  wood.  First  crop  figs  are 
called  "Brebas."  Second-crop  fruit  is  borne  in  the  axils  of 
current  leaf  growth,  on  new  wood.  Second-crop  figs  are 
called  "Summer  figs."  Brebas  are  large  figs,  not  very  rich 
in  sugar,  and  are  desirable  for  eating  fresh.  Summer  figs 
are  smaller  and  sweeter,  and  hence  are  suitable  for  drying. 

2.  Smyrna  Figs  (known  in  California  as  "Bulletin 
Smyrnas"  or  "Lobfigs").— These  bear  only  pistillate  flowers 
and  produce  fruit  only  when  caprificated  or  hand-pollinated. 
The  seeds  produced  are  perfect,  and  it  is  the  aromatic  quali- 
ties in  them  to  which  the  superiority  of  Smyrna  figs  is  due. 
Smyrna  figs  are  now  grown  with  success  in  California. 

3.  San  Pedro  Figs. — These  produce  but  one  crop,  the 
Brebas.  The  second  crop  possesses  only  pistillate  flowers, 
and  the  fruit  drops  before  reaching  maturity.  First-crop 
figs  bear  mule  flowers  only. 

4.  Adriatic  Figs. — This  is  a  type  of  figs  in  which  the 
Brebas  require  caprification,  while  the  second  crop  does  not. 

5.  Erinocyce  Figs. — This  is  a  rare  type  in  which  the  first 
crop  is  inedible,  producing  staminate  and  gall  flowers, 
while  the  second  crop  has  both  pistillate  and  gall  flowers. 


276  BOTANY  OF  CROP  PLANTS 

6.  Cordelia  Figs. — These  are  also  rare.  They  are  an  edible 
fig  possessing  only  staminate  flowers. 

7.  Caprifigs. — This  is  considered  to  be  the  original  type 
of  fig  from  which  all  the  above  have  come.  They  grow  wild 
in  southern  Europe,  northern  Africa  and  western  Asia. 
There  are  three  crops  of  Caprifigs:  First  crop  (profichi), 
which  bear  staminate  and  gall  flowers,  but  not  pistillate. 
The  receptacles  form  in  the  autumn,  maturing  the  following 
June  or  July.  Second  crop  {mammoni) ;  staminate,  pistillate 
and  gall  flowers  occur  in  the  figs  of  this  crop.  The  fruit 
matures  in  August  or  September.  Third  crop  (mamme); 
the  figs  of  this  crop  have  only  staminate  and  gall  flowers. 
They  hibernate  over  the  winter,  reaching  maturity  in  March 
or  April. 

Uses  of  Figs. — Figs  are  grown  chiefly  for  the  fruit.  This 
is  sometimes  eaten  fresh,  but  is  more  commonly  dried  for 
transportation.  Brebas  are  juicier  than  Summer?  figs, 
and  hence  are  more  desirable  for  eating  raw.  Summer  figs 
and  Smyrnas,  however,  are  richer  in  sugar,  and  for  this 
reason  are  better  for  drying.  A  limited  area  of  land  near 
Smyrna  produces  the  largest  percentage  of  dried  figs.  How- 
ever, the  industry  of  drying  figs  is  growing  in  California. 
Here,  the  figs  are  washed  in  salt  water,  dried,  and  rewashed 
in  salt  water,  graded,  and  packed.  Fig  syrup  is  a  medicinal 
product  of  the  fruit.  The  fig  tree  is  sometimes  planted  for 
ornament  and  shade,  and  the  soft,  light,  but  elastic  wood 
finds  considerable  use. 

CANNABIS  SATIVA  (Hemp) 

Description. — The  common  hemp  is  a  stout,  erect,  branch- 
ing annual,  5  to  15  feet  high.  The  main  stem  is  hollow  and 
produces  a  few  branches  near  the  top.  The  leaves  are  alter- 
nate   above    and    opposite    below.     They    are .  compound, 


MORACE.K 


-/  / 


(ligilatf,  with  Uw  to  eleven  linear-laiueolate,  i>()inte<l  and 
serrate  leallets.  Hemp  is  diceeious.  The  slam'nuilr  iii- 
Jlofcscciiccs  (Fi,^.  1 08,  A) 
are  in  axilhir}-,  narrow  and 
loose  panicles,  the  pisliUalr 
in  erect,  leafy  spikes,  also 
axillary.  The  stam'nialc 
flower  is  borne  on  a  slender 
l)editel  subtended  by  a 
bracteole;  it  has  five  dis- 
tinct sepals  and  five  short 
stamens.  Each  pistillalr 
flower  (Fig.  108,  B)  is  sub- 
tended by  a  leafy  bract, 
and  possesses  a  single, 
thin,  entire  calyx  segment, 
wrapped  about  the  ovary. 
The  ovary  has  two  thread- 
like feathery  stigmas. 
Hemp  is  wind-pollinated. 
The  ovary  matures  into 
an  ovoid,  hardachene. 
The  curved  embryo  is 
imbedded  in  a  tlesh\'  endo- 
sperm.  'i'he  fruits  of 
hem  J)  an-  much  larger 
and  hea\ier  when  grown 
in  a  moist  habitat  than 
when  grown  in  a  dry 
one. 


hilc  t\< 


llciiii'   (Cmn.il 

irt    sali\ 

st;iininaU-  i)l;int 

;    B.  sin 

.M-.      {B  ,ill<-r  \V 

yssidlo.) 

Geographical.— Tlu-  niitixc  lionu'  of  common  lu  mp  is  ci-ntral  arui  western 
Asia.  It  lias  spread,  as  a  result  of  lullivalion,  throuRliout  liurope,  .\sia  and 
America.  In  many  places,  it  has  escaped  from  cultivation  and  become  a 
rather  troublesome  weed. 


278 


BOTANY    OF    CROP    PLANTS 


Varieties.  Nearly  all  hemp  grown  in  this  country  is  of 
Chinese  origin,  'i'he  Japanese  hemp  is  identical,  or  very 
similar,  to  Chinese  hemp.  European  varieties  (Piedmont, 
Neapolitan,  Hungarian,  and  Russian),  often  termed  Smyrna 
types,  dififer  from  the  Chinese  and  Japanese  ones  in  that  the 
plants  are  shorter,  the  growth  is  more  compact,  the  seeds  are 
in  denser  clusters  and  earlier  in  maturing.  'J'he  best  Cjuality 
of  hemp  liber  comes  from  Italy. 


Fig.  109.-  Cutting  hemp,  Kentucky.  {From  Essenlials  of  Geography, 
Second  Book.  Copyriglil,  1916,  by  Albert  Perry  Brighain  a>id  Charles  T. 
McFarlaiir.     American  Book  Company,  Publishers.) 

The  Hemp  Industry  in  the  United  States.—  Since  about  the 
year  1906,  there  has  been  a  slight  decline  in  the  domestic 
production  of  hemp.  This  falling  off  has  been  due  to  the 
difliculty  of  obtaining  laborers  to  do  the  work  of  retting, 
breaking,  and  preparing  the  liber  for  the  market;  to  the  lack 
of  development  of  labor-saving  machinery;  to  the  fact  that 
greater  profits  are  derived  from  raising  other  crops  in  hemp- 


HORACES  279 

growing  regions;  and  to  the  greater  use  of  other  fibers  in  the 
manufacture  of  products  formerly  made  of  hemp. 

Kentucky  began  to  raise  hemp  in  1775,  and  that  State  now 
leads  in  hemp  production.  Kentucky  now  furnishes  the 
seed  for  nearly  all  of  the  hemp  grown  for  fiber  in  the  United 
States;  the  hemp  from  this  State  is  mostly  of  Chinese 
origin.  The  chief  hemp-growing  States  are  Kentucky,  Cali- 
fornia, Nebraska,  Indiana,  New  York,  and  Wisconsin. 

Preparation  of  Hemp  for  Maiket—Har vesting  Hemp. — 
In  some  places,  hemp  is  still  harvested  by  hand  with  a  reaping 
knife  or  hemp  hook.  However,  in  most  hemp-growing  dis- 
tricts, sweep-rake  reapers,  mowing  machines,  or  self-rake 
reapers  are  used. 

The  hemp  stalks,  usually  8  to  14  feet  long,  are  bound  into 
bundles  about  10  inches  in  diameter,  and  shocked.  They 
are  allowed  to  stand  in  the  shocks  for  ten  to  fifteen  days,  or 
until  they  are  dry  enough  to  be  stacked. 

There  is  an  advantage  in  stacking  hemp,  in  that  it  rets 
more  quickly  and  more  uniformly  than  hemp  that  is  taken 
directly  from  the  shock.  Furthermore,  .the  stacking  of 
hemp  improves  the  quality  and  yield  of  the  fiber. 

Retting. — This  is  a  process  in  which  the  substances  sur- 
rounding the  bast  fibers  are  partially  dissolved,  thus  allowing 
the  fibers  to  be  separated  from  the  wood  ("hurd")  and  thin 
outer  bark,  and  from  each  other.  This  separation  is  due  to 
the  decomposing  action  of  bacteria,  in  fact  the  retting  organ- 
ism has  been  isolated  and  grown  in  pure  cultures.  There  are 
two  commercial  methods  of  retting:  dew-retting  and  water- 
retting.  The  former  is  the  common  method  in  this  country. 
The  hemp  stalks  are  spread  out  in  thin,  even  rows  on  the 
ground,  where  they  are  exposed  to  alternate  freezing  and 
thawing,  or  to  cool,  moist  weather.  The  process  of  retting  is 
complete  when  the  bark  separates  easily  from  the  woody 


28o  BOTANY  OF  CROP  PLANTS 

portion  ("hurd")  of  the  stem.  Water-retting  is  practised  in 
European  and  Asiatic  countries.  The  stalks  are  immersed  in 
streams,  ponds,  or  artificial  tanks. 

Breaking. — In  the  breaking  process,  the  inner  cyhnder  of 
wood  is  broken  in  pieces,  which  permits  it  to  be  removed, 
leaving  behind  the  long  bast  or  hemp  fibers.  The  removal  of 
the  broken  pieces  of  woody  tissue  is  known  as  scutching.  In 
this  country,  both  hand  breaks  and  machine  breaks  are  in 
use.  The  stems  must  be  dry  before  breaking,  so  as  not  to 
injure  the  fibers. 

Hackling. — The  long,  straight  hemp,  known  as  rough 
hemp,  is  sorted  and  hackled  by  hand.  In  the  process  of 
hackling,  the  rough  fiber  is  combed  out  by  drawing  it  over 
coarse  hackles;  the  product  is  known  as  "single-dressed 
hemp."  This  may  be  combed  out  by  drawing  it  over  finer 
hackles,  thus  preparing  a  fiber  known  as  "double-dressed 
hemp."  Double-dressed  hemp  brings  the  better  price  on  the 
market.  Hemp  tow  is  from  broken  or  tangled  stalks,  and  is 
inferior  in  quality  to  the  long,  straight  hemp. 

Uses  of  Hemp. — Hemp  is  grown  primarily  for  its  fiber. 
The  fibers  are  in  the  bast  and  average  about  20  millimeters 
in  length.  They  are  of  the  best  quality  if  the  plants  are  cut 
when  staminate  plants  are  in  full  bloom.  If  cut  too  early, 
the  fibers  lack  strength,  and  if  harvested  too  late  they  are 
coarse  and  brittle. 

Hemp  fiber  is  put  to  a  variety  of  uses.  It  is  used  in  the 
manufacture  of  sail  cloth,  yacht  cordage,  binder  twine, 
tying  twine,  carpet  yarns,  carpet  thread,  sacking,  bagging, 
rope,  upholstery  webbing,  and  belt  webbing.  The  ravelings 
of  hemp  rope,  termed  "oakum,"  are  used  for  calking  seams 
of  wooden  boats  and  joints  of  iron  pipe,  in  pumps,  engines, 
and  other  machinery.  The  seed  of  hemp  is  often  fed  to 
poultry  and  cage-birds.     Moreover,  the  seed  contains  20  to 


HORACES  281 

25  per  cent,  of  an  oil,  which  is  sometimes  extracted  and  used 
as  a  substitute  for  Unseed  oil.  The  drug  Cannabis  indica 
is  derived  from  the  stems  and  leaves  of  common  hemp,  which 
under  the  hot  climatic  conditions  of  India,  chiefly,  develop  a 
volatile  oil  and  a  strong  narcotic  resin  (cannabin).  These 
substances  are  secreted  by  the  glandular  hairs  on  stems  and 
leaves.  They  are  not  produced  to  any  extent  in  cold  climates. 
Hemp-seed  oil  is  used  for  making  soft  soaps,  as  a  paint  oil, 
and  low  grades  are  utilized  for  certain  varnishes.  Recent 
tests  show  that  a  fair  quaHty  of  paper  can  be  made  from 
hemp  "hurds." 

The  chief  fiber  competing  with  hemp  is  jute.  Jute  is 
produced  in  India  from  two  species  of  plants,  Corchorus 
capsularis  and  Corchorus  olitorius.  It  is  used  extensively 
for  the  manufacture  of  sugar  sacks,  gunny  sacks,  burlaps, 
grain  sacks,  and  wool  sacking.  It  is  about  two-thirds  as 
strong  as  hemp  fiber  of  the  same  weight,  and  is  not  as  durable. 
Although  hemp  has  been  used  to  some  extent  in  the  manu- 
facture of  binder  twine,  most  of  the  binder  twine  now  is  made 
from  the  fibers  of  sisal  and  abaca. 

Sisal  Hemp. — The  main  center  of  production  for  Agave 
fibers  is  Yucatan  in  Mexico.  On  the  low  limestone  plains  of 
this  country,  Agava  sisalana  thrives.  It  belongs  to  a  differ- 
ent family  (Amaryllidaceae)  than  that  to  which  common 
hemp  belongs.  This  plant  yields  the  well-known  "sisal 
hemp"  or  "hennequin."  The  plant  is  cultivated.  This 
country  now  imports  large  quantities  of  sisal  hemp,  all  of 
which  is  from  Yucatan.  It  is  used  mainly  in  the  manufac- 
ture of  binder  twine.  About  200,000,000  pounds  of  binder 
twine  are  required  annually  to  harvest  the  grain,  corn,  and 
flax  crops  of  the  United  States.  Practically  all  of  the  fiber 
from  which  this  twine  is  made  comes  from  the  Agave^plant 
of  Yucatan. 


BOTANY   OF   CROP   PLANTS 


References 


Bailey,  L.  H.:  Mulberries.     Cornell  Agr.  Exp.  Sta.  Bull.  41:  223-243,  1892. 

Sketch  of  the  Evolution  of  Our  Native  Fruits.     The  Macmillan  Co.,  1898. 
Briant,  Lawrence,  and  Meacham,  C.  S.  :  Hops.     The  Influence  of  Climate, 

Ripeness,  Soil,  Drying,  and  General  Manipulation  on  the  Value  of  Hops. 

Jour.  Fed.  Ins.  Bre-wing,  2:  423,  1896. 
Chapman,  A.  C:  The  Essential  Oil  of  Hops.     Proc.  Chem.  Soc.  (London), 

9:  177,   1893;   10:  227-229,  1894.     Jour.  Chem.  Soc.  (London)  Trans., 

67:  54-63,  1895a.     Jour.  Fed.  Inst.  Brewing,  4:  224-233,  1898.     Jour. 

Chem.  Soc.  (London)  Trans.,  83:  505-513,  1903. 
The  Hop  and  its  Constituents.     A  Monograph  on  the  Hop  Plant.    London, 

1905.     Published  by  Brewing  Trade  Review. 
Chedsey,  M.:  The  Influence  of  Pollination  upon  the  Development  of  the  Hop 

{Humulus  lupulus).     Plant  World,  8:  281-283,  i905- 
Cook,  O.  F.:  Sexual  Inequality  in  Hemp.     Jour.  Hered.,  5:  203-206,  1914. 
EiSEN,  GusTAv:  Edible  Figs,  their  Culture  and  Curing.     U.  S.  Dept.  Agr. 

Div.  Pom.  Bull.  5:  1-33,  1897. 
The  Fig:  Its  History,  Culture,  and  Curing.     U.  S.  Dept.  Agr.  Div.  Pom. 

Bull.  9:  1-317,  1901. 
Biological  Studies  on  Figs,  Caprifigs,  and  Caprification.     Proc.  Cal.  Acad. 

Sci.,  ser.  2,  vol.  5:  897-1003,  1896. 
Gross,  E.:  Hops  in  Their  Botanical,  Agricultural,  and  Technical  Aspects 

and  as  an  Article  of  Commerce.     Scott,  Greenwood  &  Co.,  London,  1900. 

Transl.  from  German  by  C.  Salter. 
Howard,  A.:  Hop  Experiments  in  1904.     Councils  Kent  and  Surrey.     South- 
eastern Agr.  Col.,  Wye,  Bull,  i:  1-29,  1904-5. 
The  Influence  of  Pollination  on  the  Development  of  the  Hop.     Jour.  Agr. 

Sci.,  i:  49-58,  1905. 
Howard,  L.  O.  :  The  Present  Status  of  the  Caprifig  Experiments  in  California. 

U.  S.  Dept.  Agr.  Div.  Ent.  Bull.  20  (new  ser.):  28-35,  1899. 
Smyrna  Fig  Culture  in  the  United  States.     U.  S.  Dept.  Agr.  Yearb.,  1900: 

76-106,  1901. 
Matthews,  J.  M.:  The  Textile  Fibers:  Their  Physical,  Microscopical,  and 

Chemical  Properties.     John  Wiley  &  Sons,  191 1. 
Myrick,  H.:  The  Hop:  Its  Culture  and  Curing,  Marketing,  Manufacture. 

Orange  Judd  Co.,  1899. 
Power,  F.  B.,  Tutin,  F.,  and  Rogerson,  H.:  The  Constituents  of  Hops. 

Jour.  Chem.  Soc.  (London),  103:  1267-1292,  1913. 
Rabak,  F.:  Aroma  of  Hops:  A  Study  of  the  Volatile  Oil  with  Relation  to  the 

Geographical  Sources  of  the  Hops.    U.  S.  Dept.  Agr.  Jour.  Agr.  Research, 

2:  115-159,  1914. 


MORACEiE  283 

Salmon,  E.S.,  and  Amos,  A.:  On  the  Value  of  the  Male  Hop.  Jour.  Southeast. 
Agr.  Col.,  Wye,  17:  365-391,  1908. 

Salmon,  E.  S.  :  The  Pollination  and  Fertilization  of  Hops  and  the  Characteris- 
tics of  "Seeded"  and  "Seedless"  Hops.  Jour.  Agr.,  21:  22-31,  123-133, 
1914. 
The  Pollination  and  Fertilization  of  Hops  and  the  Characteristics  of 
"Seeded"  and  "Seedless"  Hops.  Jour.  Bd.  Agr.  (London),  2:  123- 
^33',  3-  23-220;  20:  953-966;  21:  22-31,  1914. 

Schmidt,  J.:  Investigations  on  Hops,  V.  On  the  Aroma  of  Hops.  Compt. 
Rend.  Lab.  Carlsberg,  11:  149-163,  1915. 

SxocioJERGER,  W.  W. :  Change  of  Sex  in  Humulus  Lupulus  not  Due  to  Trau- 
matism.    Abs.  in  Sci.,  n.s.  31:  632,  1910. 

TouRNOis,  J.:  Sexual  Studies  of  the  Hop  Plant.  Ann.  Aci.  Nat.  Bot.,  9  ser., 
19:  49-191,  1914- 

WiNGE,  O. :  The  Pollination  and  Fertilization  Processes  in  Humulus  Lupulus 
L.  and  H.  Japonicus  Sieb.  et  Zucc.  Comp.  Rend.  Lab.  Carlsberg, 
11:  1-46,  1914. 


CHAPTER  XXII 


POLYGONACE^  (Buckwheat  Family) 

Herbaceous  representatives  of  this  family  are  largely  found 
in  temperate  regions,  tree- 
like species  in  Anierican 
tropics,  while  shrubby  ones 
are  limited  to  western  Asia. 
There  are  about  30  genera 
and  800  species.  Rhubarb 
and  buckwheat  are  the  prin- 
cipal cultivated  members, 
while  a  number  of  species  of 
Rumex  (dock) ,  and  of  Polygo- 
num (knotweed,  bind-weed, 
etc.)  are  bad  weeds. 

Stems.— The  stems  are 
conspicuously  jointed  and 
usually  swollen  at  the  joints. 
The  leaves  are  alternate 
(Fagopyrum),  opposite  {Ma- 
counastrum) ,  or  whorled 
(mountain  sorrel,  Oxyria 
digyna).  They  are  mostly 
entire,  rarely  lobed  or  divided. 
The  stipules,  with  a  few  ex- 
ception s,  are  membranous, 
sheathing,  and  united  to 

form  a  very  characteristic  structure,  the  ocrea  (plu.  ocreae) 

(Fig.  no). 

284 


Fig.  1 10. — Leaf  of  common  buckwheat 
(Fagopyrum  vulgare).      X  i. 


POLYGONACE.E  285 

Inflorescences. — The  inflorescences  vary  a  great  deal 
within  the  family;  in  buckwheat  they  are  panicled  racemes, 
in  Polygonum  spp.,  terminal  or  axillary  spike-hke  racemes, 
in  Eriogonum  spp.,  cymes,  umbels  or  heads.  The  cyme  is  a 
determinate  type  of  inflorescence.  In  this  type,  the  terminal 
flower  is  the  oldest  and  subsequent  ones  open  in  order  from 
the  inside  to  the  outside  of  the  inflorescence  (centrifugal  open- 
ing of  the  inflorescence).  In  the  head  type  of  inflorescence, 
so  well  exemphfied  by  the  dandelion  or  sunflower,  the  flowers 
are  crowded  on  the  receptacle;  the  stalk  of  each  flower  is 
very  short  or  entirely  absent;  it  is  an  indeterminate  type. 

Flowers. — The  flowers  are  small,  mostly  perfect,  rarely 
dioecious  or  monoecious,  and  radially  symmetrical.  In 
the  genus  Eriogonum,  the  flowers  are  subtended  by  a  five-  to 
eight- toothed  involucre.  The  calyx  consists  of  two  to  six 
segments  which  are  below  the  ovary  and  free  from  it;  the 
segments  are  in  one  or  two  series,  often  imbricated  (over- 
lapping), and  the  inner  or  both  series  are  petaloid  (resembling 
petals).  There  are  no  petals.  The  stamens  vary  from  two 
to  nine;  in  perfect  flowers,  they  are  attached  near  the  base 
of  the  calyx,  while  in  staminate  ones,  they  may  be  crowded 
on  a  central  disk;  the  filaments  are  fihform,  mostly  distinct 
but  sometimes  united  in  a  ring  at  the  base,  and  commonly 
dilated  at  the  base;  the  anthers  possess  two  cells,  and  are 
longitudinally  dehiscent.  The  pistil  is  sohtary.  The  su- 
perior ovary  is  one-celled,  three-angled  or  compressed,  rarely 
four-angled,  and  usually  sessile ;  the  styles  are  most  frequently 
three  in  number,  rarely  two  or  four,  and  attached  to  the  apex 
of  the  ovary;  the  stigmas  are  capitate  (head-shaped)  or 
tufted,  and  sometimes  two-cleft.  Within  each  ovary  there 
is  a  single  ovule. 

Fruit. — The  fruit  is  a  three-angled  (rarely  four-angled) 
achene,  about  which  is  frequently  the  persistent  calyx;  the 


286 


BOTANY   OF   CROP   PLANTS 


pericarp  is  hard  or  leathery.  The  single  seed  in  each  fruit 
assumes  the  shape  of  the  pericarp;  the  seed  coat  (testa)  is 
membranaceous,  the  endosperm  is  abundant  and  mealy,  and 
the  embryo  is  straight  or  curved. 

Key  to  Pkincipal  Genera 

Flowers  subtended  by  involucres;  ocreae  wanting,  Eriogonum. 
Flowers  not  subtended  by  involucres;  ocreae  present. 
Calyx  six-parted  (rarely  four). 

Stamens  nine  (very  rarely  six),  Rheum  (rhubarb). 
Stamens  six,  Rumex  (dock). 
Calyx  five-parted  (rarely  four). 
Achene  much  surpassing  the  calyx,  Fagopyrum  (buckwheat). 
Achene  enclosed  by  the  calyx.  Polygonum  (bistort,  persicaria,  knot  weed, 
bindweed,  etc.). 

RHEUM  RHAPONTICUM  (Rhubarb,  Pie  Plant)     , 

Roots,  Stems,  Leaves,  Flowers. — This  plant  is  a  perennial 
from  large,  quite  woody  rhizomes  which  have  a  fibrous  and 


Fig.   III. — Rhubarb    (Rheum)    flower,    external    view,    median  lengthwise 
section,  and  with  perianth  and  stamens  removed.     (After  Lilrssen.) 

well-developed  root  system.  The  rhizome  is  used  in  the 
propagation  of  the  plant.  In  the  spring,  a  number  of  large 
leaves  are  sent  up  from  the  underground  stem,  and,  later  in 


POLYGONACE/E 


287 


the  season,  there  arise  flower  shoots,  bearing  elongated  leafy 
inflorescences,  crowded  with  small  whitish  flowers.  Unless 
seed  is  desired,  flower  shoots  should  be  promptly  removed, 


i.2.  ^Rhubarlj  ^ Rheum  rhaponticuiu)  plauL  iu  trviic. 


as  they  require  considerable  food  supply  which  should  go 
to  the  support  of  the  roots.  The  leaves  are  large,  circular 
in  outline,  cordate  at  the  base,  and  with  sinuate  veins 
beneath;  leaf  petioles  are  semi-cylindrical  and  bear  membran- 


288 


BOTANY    OF    CROP    PLANTS 


ous  ocreas.  The  flowers  are  on  short,  jointed  pedicels  and 
occur  in  fascicles,  each  of  which  is  a  raceme;  the  entire 
inflorescence  is  paniculate.  The  flowers  (Fig.  in)  are  small, 
greenish  white  and  perfect;  the  calyx  is  six-parted,  persistent, 
and  becomes  enlarged  somewhat  in  the  fruit  (Fig.  113); 
there  are  nine  stamens;  the  ovary  is  three-angled  and  bears 
three  short,  recurved  styles,  with  large  stigmas. 


-^-V^-perj/jfen/  j/y/ej 


persiMenl 
cai\jx  lobe 


Fig. 


:i3. — Fruit  of  rhubarb  (Rheum  rhaponticum). 
cross-section.      X  5. 


.1,  external  view;  B, 


Self-pollination  is  prevented  to  a  large  degree  by  the  matu- 
ration of  anthers  before  the  stigmas.  Stigmas  of  flowers 
below  on  the  inflorescence  receive  pollen  from  the  anthers  of 
younger  flowers  borne  above  them.  Pollen  is  disseminated 
by  wind,  insects,  and  gravity. 

Fruit.-  Rhubarb  fruit  (Fig.  113)  is  an  achene  surrounded 
at  the  base  with  the  persistent  remains  of  the  perianth;  it  has 
three  broad,  thin  wings  which  are  traversed  by  a  longitudinal 
nerve  running  near  ihu  margin;  it  is  tip[)ed  l)y  a  small  per- 


POLYGONACE/E  289 

sistent  style.  The  seeds  are  three-angled,  conforming  in 
shape  to  the  fruit;  the  testa  is  (hin  and  red;  the  hiluni  and 
micropyle  are  basal;  the  endosperm  is  abundant  and  sur- 
rounds the  large,  straight  embryo,  (jood-sized  plants  can 
be  raised  from  seed  in  one  season  if  it  is  [)lanted  early.  The 
seedlings  of  rhubarb  show  interesting  xariation. 

Geographical,  and  Varieties -The  common  rhubarb  is  a 
native  of  Asia.  It  has  become  introduced  into  many  coun- 
tries of  the  temperate  cHmates.  It  is  a  cool  season  crop  that 
will  withstand  summer  heat,  and  the  roots  winter  freezing. 
It  is  claimed  that  a  number  of  the  varieties  now  grown 
are  hybrids  between  R.  rliaponlicum,  R.  undulatnm  and 
R.  palmalum.  The  principal  varieties  grown  are  J.innocus, 
Victoria  and  Monarch.  There  are  a  number  or  ornamental 
species  of  Rheum,  most  of  which  are  tlistinguished  from  com- 
mon rhubarb  by  their  more  or  less  lobed  leaves,  the  margins 
of  w^hich  may  be  coarsely  or  linely  toothed. 

Uses. — Rhubarb  or  pie  plant  is  a  vegetable  used  for  its 
large,  acid  leaf  stalks,  which  are  of  the  best  quahty  early  in 
the  season.  'J'he  leaf  stalks  are  usually  made  into  pies  or 
sauce,  and  occasionally  wine  is  made  from  the  juice. 

FAGOPYRUM  VULGARE  (Common  Buckwheat) 

Roots. — Common  l)uckwheat  is  an  annual,  from  2  to  4  feet 
tall.  It  has  a  small  root  system.  There  is  a  single  primary 
root  which  may  reach  down  to  a  distance  of  3  or  4  feet;  side 
roots  are  given  off  along  the  primary,  but  they  do  not  extend 
far  into  the  soil.  Tkickwheat  differs  from  the  true  cereals,  in 
the  possession  of  a  single  {)rinuir}-  root,  and  a  much  less 
extensive  root  system. 

Stems. — The  stems  are  quite  succulent,  smooth,  except  at 
the  nodes,  and  strongly  groo\ed.  I'>ach  seed  gives  rise  to  but 
one  stem  which  may  branch  freely,  but,  unlike  grasses,  no 
19 


290 


BOTANY   OF   CROP   PLANTS 


''suckers"  or  "tillers"  are  produced.  The  amount  of 
branching  depends  upon  the  thickness  of  seeding;  the  plants 
branch  freely  when  not  crowded  and  feebly  when  crowded. 
The  young  stems  vary  from  green  to  red,  and  turn  brown 
with  age. 


c^m 


Leaves.-  The  leaves  are  ahernaLely  arranged  on  the  stem 
and  characteristically  hastate  (halberd-shaped)  (Fig.  no),  or 
triangular  heart-shaped;  they  may  be  sessile  or  short- 
petioled,  and  bear  an  ocrea  (Fig.  1 10),  which  soon  falls  oil. 


POLYGONACE^ 


291 


Inflorescence. — The  inflorescence  is  a  raceme  .whicli  may 
be  either  paniculate  or  corymbose  (a  corymb  is  a  flat-topped 
raceme  type  of  inflorescence);  it  is  terminal  and  axillary, 
many-flowered,  and  erect  or  slightly  drooping. 


nectar  ^land 
receptacle 


Fig.  115. — Common  buckwheat  (Pagopyrum  vulgare).  A,  achene;  B, 
floral  diagram;  C,  cross-section  of  fruit;  D,  flower.  (J5  after  Wossidlo;  C  after 
Stevens.) 

Flowers. — The  flowers  (Fig.  115,  D)  are  white,  tinged  with 
pink.  There  are  no  petals  (hence  is  apetalous),  but  there  is 
a  five-parted  corolla-like  calyx  which  remains  attached  to  the 


292  BOTANY  OF  CROP  PLANTS 

base  of  the  fruit.  There  are  eight  stamens  with  glabrous, 
fihform  filaments  and  oblong  anthers.  Three  of  the  stamens 
closely  surround  the  styles  and  dehisce  outward,  while  the 
five  others  are  inserted  outside  of  these  three,  and  dehisce 
inward.  The  single  ovary  is  one-celled  and  one-ovuled  and 
bears  three  style  branches,  which  are  bent  back  in  fruit. 

The  plant  begins  to  bloom  when  quite  young  and  continues 
until  frost. 

Dimorphism  and  Pollination. — Common  buckwheat  has 
dimorphous  flowers,  i.e.,  there  are  two  forms.  One  of  these 
forms  has  short  styles  and  long  stamens,  and  the  other,  long 
styles  and  short  stamens.  This  condition  is  known  as  hetero- 
styly.  The  pollen  grains  of  short-styled  flowers  are  larger 
than  those  of  long-styled  flowers.  Usually,  all  the  flowers  on 
one  plant  are  of  one  form  or  the  other.  Occasionally,  how- 
ever, both  long-styled  and  short-styled  plants  may  bear  a 
very  few  flowers  with  styles  and  stamens  of  the  same  length. 
These  "equal-styled"  flowers  are  not  fertile.  The  seeds 
from  either  form  of  flower  will  produce  buckwheat  plants, 
some  of  which  produce  one  form  and  some  the  other. 

Buckwheat  is  regularly  visited,  by  numerous  insects. 
Heterostyly  is  a  condition  which  tends  to  prevent  self-polli- 
nation. 

Fruit. — The  mature  fruit  (Fig.  115,  A)  is  a  triangular  (some- 
times two-  or  four-angled)  crustaceous  achene,  brown, 
streaked  with  black,  or  entirely  black;  the  point  of  the 
''grain"  is  the  stigmatic  end,  while  the  opposite  end  shows 
a  fragment  of  the  flower  stalk  (pedicel),  and  small,  persistent, 
withered  calyx  lobes  which  have  become  adherent  to  the  peri- 
carp.    The  "hull"  is  the  pericarp  and  attached  portions. 

Seed. — The  single  seed  conforms  in  shape  to  the  pericarp. 
There  is  an  abundance  of  white,  dry,  floury  endosperm  in 
which  is  imbedded  the  embryo.     Buckwheat  endosperm  is 


POLYGONACE^ 


293 


more  starchy  than  that  of  wheat,  oats,  barley,  rye  and  corn, 
and  the  fat  content  is  lower.  Consequently,  buckwheat 
flour  is  low  in  percentage  of  protein  and  fat.  The  embryo 
("germ"),  however,  has  an  abundance  of  fat  and  protein,  and 
for  this  reason  "middlings,"  which  contain  the  embryo,  are  a 
valued  stock  food.  In  a  cross-section  of  the  fruit  (Fig. 
115,  C),  the  embryo  has  the  form  of  the  letter  S,  and  reaches 
from  one  of  the  three  angles  of  the  seed  to  another. 


—jtarchv 
endosperm 


Fig.   116. — Common  buckwheat  (Fagopyrum  vulgare).     Section  of  mature 
seed.     (After  Stevens.) 

Geographical.^ — Common  buckwheat  has  been  cultivated 
in  China  for  1,000  years.  It  was  introduced  into  Europe 
during  the  middle  ages.  It  was  brought  into  this  country 
by  the  early  settlers.  It  has  escaped  from  cultivation  in 
North  America,  and  is  now  common  throughout  northern 
United  States  and  Canada. 

Other  Species. — There  are  two  other  species  of  Fagopyrum, 
one  of  which,  F.  tataricum,  at  least,  has  been  cultivated  to  a 
slight  extent  in  this  country,  and  is  also  an  occasional  escape 
from  cultivation.  Tatary  buckwheat  is  distinguished  from 
the  common  form  by  the  simple  racemes,  its  rough  hull,  and 
the  wavy  fruit  angles.     It  is  cultivated  where  a  hardy  sort  is 


294  BOTANY    or   CROP   PLANTS 

needed.  The  notch-seeded  buckwheat  {F.  emarginatum), 
a  form  cultivated  in  northeastern  India  and  China,  is  dis- 
tinguished from  the  preceding  by  having  the  angles  of  the 
smooth  hull  prolonged  into  wide,  rounded  wings. 

Varieties. — Three  varieties  of  common  buckwheat  are 
grown  in  the  United  States:  Japanese,  silver  hull,  and  com- 
mon gray.  They  may  be  distinguished  by  the  following 
key: 

Key  to  Varieties  of  Common  Buckwheat 

Faces  of  grain  slightly  concave;   angles   extended  into  very  short   wings, 

Common  gray. 
Faces  of  grain  flat;  angles  not  extended  into  wings. 

Grain  small  and  plump,  Silver  hull. 

Grain  large  and  not  so  plump,  Japanese. 

Environmental  Relations. — Buckwheat  is  a  temperate- 
climate  plant,  finding  the  best  conditions  for  growth  where 
the  summers  are  cool  and  moderately  moist.  Dry,  hot 
weather  is  inimical  to  the  proper  setting  of  the  fruit.  Accord- 
ing to  the  work  of  Briggs  and  Shantz,  buckwheat  has  a  water 
requirement  intermediate  between  that  of  barley  and  oats, 
the  actual  amount  being  578.  Buckwheat  is  known  to  do 
well  on  poor  soils,  even  those  in  which  the  drainage  is  such  as 
to  make  it  impossible  to  grow  the  small  cereals  profitably. 

Uses. — The  principal  use  of  buckwheat  is  in  the  manu- 
facture of  pancake  flour.  As  a  food  for  stock,  it  is  used  in 
various  forms.  The  whole  grain  is  sometimes  fed  to  poul- 
try, hogs  and  cattle.  Usually,  however,  the  hulls  are  re- 
moved from  the  grain,  and  the  seeds  ground,  before  feeding 
to  hogs.  The  middlings  (hulls  mixed  with  bran)  are  prized 
as  a  stock  feed.  Buckwheat  straw  is  used  both  as  a  feed 
and  a  bedding  for  stock.  Honey  from  buckwheat  flowers 
has  always  possessed  a  high  reputation  for  flavor.     Buck- 


POLYGONACEiE  295 

wheat  will  grow  well  on  poor  soil — a  soil  that  will  not  support 
true  cereals.  Therefore,  it  may  be  used  as  a  green-manure 
crop. 

References 

Morse,  J.  F.:  The  New  Rhubarb  Culture.     Orange  Judd  Co.,  191 2. 
Stevens,  N.  E.:  The  Morphology  of  the  Seed  of  Buckwheat.     Bot.  Gaz., 

53:  S9-66,  1912. 
Observations  on  Heterostylous  Plants.     Bot.  Gaz.,  53:  277-308,  191 2. 
TsuTSUMi,   Ochimura:  Studies   on  the  Buckwheat.     Bot.   Mag.  (Tokyo), 

8:  288-291;  417-421,  1894. 
Williams,  F.  N.:  Primary  Characters  in  the  Species  of  Rheum,  29:  292-295, 

1891. 


CHAPTER  XXIII 
CHENOPODIACE^  (Goosefoot  Family) 

This  family  is  widely  distributed  geographically.  They 
are,  for  the  most  part,  saline  plants  found  near  the  ocean  or 
in  deserts  and  steppes.  They  are  characteristic  plants  of  the 
alkaline  swamps  and  meadows  of  the  western  United  States. 
Plants  that  are  able  to  grow  in  soils  very  rich  in  salts  are 
designated  halophytes.  Of  course  the-  salinity  of  the  soil 
solution  retards  the  rate  of  water  intake  by  the  roots,  and, 
consequently,  halophytic  plants  are  found  with  structural 
adaptations  which  prevent  a  rapid  loss  of  water  from  the 
leaves.  Our  most  typical  halophytic  plants  are  found  within 
the  goosefoot  family. 

From  an  economic  standpoint,  the  family  is  of  consider- 
able importance.  The  principal  cultivated  forms  are  the 
beet  and  spinach.  A  large  number  are  weeds,  chief  of  which 
are  goosefoot,  pigweed,  lamb's  quarters,  strawberry  blite, 
and  Russian  thistle. 

Habit,  Stems  and  Leaves. — Members  of  the  family  are 
annual  or  perennial  herbs,  or  shrubs  {A  triplex,  saltbush). 
The  stems  are  cylindrical  or  angled,  erect  or  decumbent. 
The  leaves  are  usually  alternate,  rarely  opposite,  without 
stipules,  simple,  and  entire,  toothed  or  lobed. 

Inflorescence  and  Flowers. — The  flowers  may  occur  in 

panicled  spikes  (beet),  or  in  globular,  axillary,  sessile  heads 

(Blitum  capitatum,  strawberry  blite)  or  sometimes  they  are 

solitary  in  the  axils  {Salsola,  Russian  thistle).     The  flowers 

296 


CHENOPODIACEiE  297 

are  usually  small,  greenish,  and  bractless  (Sarcobatus,  grease- 
wood),  or  bracteolate  (Beta).  They  are  perfect  {Beta),  pis- 
tillate (Kochia),  polygamous  {Kochia),  monoecious  (Sar- 
cobatus), or  dioecious  {Atriplex  spp.)  They  are  usually  regu- 
lar. There  are  no  petals.  The  calyx  is  three-  to  five-lobed 
or  parted,  rarely  of  one  sepal  (Mowo/e/jw),  or  is  entirely  want- 
ing in  the  pistillate  flowers  of  some  genera  {Atriplex).  The 
calyx  is  persistent  in  the  fruit.  There  are  usually  as  many 
stamens  as  lobes  of  the  perianth,  rarely  fewer 
{Chenopodium  spp.);  the  filaments  are  com- 
monly slender  and  bear  longitudinally  dehis- 
cent, two-celled  anthers.  The  ovary  is 
superior,  free  from  the  calyx  and  one-celled; 
the  styles  are  terminal,  short  or  elongated, 
one  to  three  in  number,  and  bear  capitate 
stigmas.     It  has  a  single,  erect  ovule. 

Fruit. — The  mature /rw^V  is  a  utricle  (one-  Fig.  117.—^, 
seeded  fruit  with  a  loose  pericarp)  with  mem-  sarc^obl'Tif^  b, 
branous,  leathery,  or  thin  pericarp.  The  annular  embryo 
seeds  may  possess  an  abundance  of  endo- 
sperm {Beta,  Eurotia,  etc.),  or  none  {Sarcobatus,  Salsola); 
the  embryo  is  spirally  coiled  (Fig.  117)  {Salsola),  annular 
{Beta),  or  conduplicate  {Salicornia). 

Key  to  Principal  Genera 

Embryo  spirally  coiled  (Fig.  117);  endosperm  little  or  none. 
Shrubs,  Sarcobatus  (greasewood). 
Herbs,  Salsola  (Russian  thistle). 
Embryo    not    spirally    coiled,    partly    or    completely  annular   (Fig.  117); 
endosperm  abundant. 
Flowers  perfect  (polygamous  in  Kochia). 
Calyx  with  five  lobes,  about  the  base  of  which  is  developed  a  wing,  Kochia. 
Calyx  wingless,  persistent. 
Lobes  of  calyx  becoming  fleshy  and  bright  red,  Blitum  (strawberry 
blite). 


298 


BOTANY   OF   CROP  PLANTS 


Lobes  of  the  calyx  not  becoming  fleshy,  and  never  red  in  color. 
Developing  large  fleshy  tap  roots,  Beta  (beet). 
Tap  roots  not  fleshy,    Chenopodium  (goosefoot,  lamb's  quarters, 
pig- weed). 
Flowers  monoecious  or  dioecious. 
.    Bractlets  silky-hairy,  Eurotia  (winter  sage). 
Bractlets  not  silky-hairy. 

Pistillate  flowers  without  a  calyx,  Airiplex  (orache). 
Pistillate  flowers  with  a  calyx,  Spinacia  (spinach). 

SPINACIA  OLERACEA  (Spinach) 

Description. — Spinach  is  an  erect,  smooth,  annual  herb. 
Early  in  the  season,  it  throws  out  a  number  of  large  leaves, 
crowded  near  the  ground  surface.  Somewhat  later,  a  flower 
stalk  is  sent  up  to  a  distance  of  2  or  3  feet.     The  leaves  are 


Fig.  118. — Spinach  (Spinacea  oleracea).  A,  pistillate  flower  of  prickly- 
seeded  spinach;  B,  staminate  flower  of  same;  C,  fruit  of  smooth-seeded 
spinach;  D,  fruit  of  prickly-seeded  spinach. 

large,  alternate,  petioled,  and  triangular-ovate  or  arrow- 
shaped  in  outhne.  The  flowers  occur  in  axillary  clusters. 
They  are  dioecious.  The  staminate  flowers  (Fig.  118,  B) 
have  a  four-  to  five-parted  calyx  and  four  to  five  stamens 
inserted   at   the   base   of   the   perianth.    Pistillate  flowers 


CHENOPODIACE^  299 

(Fig.  118,  A)  have  a  two-  to  four-divided  perianth  which  en- 
closes the  fruit.  The  single  ovary  bears  four  to  five  stigmas, 
united  at  the  base.  The  mature  fruit  (Fig.  118,  C,  D)  is  a 
utricle  consisting  of  a  compressed  seed  surrounded  by  the 
cartilaginous  calyx  lobes,  which  are  either  smooth  or  spiny, 
and  by  a  membranous  pericarp.  The  seed  is  compressed, 
about  the  size  of  beet  seed,  and  has  an  annular  embryo 
surrounding  the  floury  endosperm. 

Spinach  is  a  native  of  southwestern  Asia.  It  has  become 
widely  spread  in  cultivation.  It  is  a  cool-season  crop  re- 
quiring an  abundance  of  water.  It  runs  to  seed  in  warm 
weather. 

Other  Plants  Named  "Spinach.**— There  are  two  types 
of  "spinach"  which  do  not  belong  to  the  genus  Spinacia: 
New  Zealand  Spinach  {Tetragonia  expansa)  and  Mountain 
spinach,  or  or  ache  (A  triplex  hortensis).  New  Zealand 
spinach  or  New  Zealand  ice  plant,  is  a  member  of  the  family 
Mesembryaceae,  and  a  native  of  New  Zealand.  It  is  grown 
as  summer  "greens."  The  plant  is  low,  but  profusely 
branching  and  spreading;  the  numerous,  upright  lateral 
branches  are  beset  with  tender  leaves;  the  tips  of  these 
branches  are  the  edible  portion  of  the  plant.  The  alternate 
triangular  leaves  are  rather  fleshy;  the  flowers  are  axillary, 
small,  yellowish  green,  and  without  petals;  the  fruit  is 
nut-like,  and  has  one  to  nine  locules,  each  of  which  is  one- 
seeded.  Mountain  spinach  or  orache  is  more  closely  re- 
lated to  the  common  species,  belonging  in  fact,  to  the  same 
tribe.  It  is  a  plant  4  to  6  feet  tall,  branching,  and  bears  an 
abundance  of  fruit.  It  not  only  differs  from  common  spin- 
ach in  its  more  erect  habit  but  in  its  floral  and  fruit  characters. 
The  pistillate  flowers  do  not  have  a  perianth,  but  in  fruit 
the  seed  is  enclosed  by  a  pair  of  compressed  bracts  which 
become  enlarged  and  wing-like. 


300  BOTANY  OF  CROP  PLANTS 

Groups  of  True  Spinach. — Kinney  places  the  varieties  of 
true  spinach  {Spinacia)  into  four  types  or  groups,  which  may 
be  distinguished  by  the  following  key: 

Key  to  Groups  of  Spinach 

"Seeds"  prickly,  Prickly-seeded  group. 
"Seeds"  smooth. 

Ends  and  lobes  of  leaves  rounded;  plants  compact  in  habit,  Round-leaved 

group. 
Ends  and  lobes  of  leaves  more  or  less  pointed. 

Plants  large,  leaves  long,  and  spreading  on  the  ground.  Thick-leaved 

group. 
Plants  not   so   spreading,  more   vase-form  and    erect,  on  account  of 
the  stronger  leaf  stalks,  Norfolk  or  Bloomsdale  group. 

It  was  formerly  thought  that  prickly-seeded  spinach 
was  more  hardy  than  the  smooth-seeded  varieties,  but  a 
number  of  the  latter  have  proven  quite  as  hardy  as  prickly- 
seeded  ones.  Norfolk,  Bloomsdale,  Curled  Savoy,  and 
American  Curled  are  important  varieties  in  the  Norfolk 
group;  Victoria  and  Long  Standing  in  the  round-leaved  group; 
Broad-leaved  Flanders,  Viroplay  and  Long  Season  in  the 
thick-leaved  group. 

Spinach  is  one  of  the  foremost  plants  for  ** greens,"  or  for 
use  as  a  pot  herb. 

BETA  VULGARIS  (Beet) 

Botanical  Groups. — The  above  is  the  only  species  of  the 
genus  Beta  of  any  economic  importance.  It  is  a  complex 
species,  however,  separated  into  a  number  of  rather  distinct 
groups  as  follows: 

1.  Sugar  beet. 

2.  Mangel-wurzels  or  mangels. 

3.  Common  garden  beet. 


CIlENOPODIACEyE  3OI 

4.  Leaf  beets. 
(d)   Chard  or  Swiss  chard. 
(b)  Ornamental  or  foHage  beets. 

The  Wild  Beet.  .  Along  the  coast  of  southern  Europe, 
there  grows  a  perennial  sea  beet  (Beta  marilima)  with  a 
tough,  slender  root.  It  is  considered  by  some  that  the  culti- 
vated groups  of  beets  have  been  derived  from  some  form  of 
this  wild  beet. 

SUGAR  BEET 

Habit. — The  sugar  beet  is  a  biennial,  storing  up  food  the 
first  }car  in  the  crown  (fleshy  stem)  and  tap  root  from  which 
aerial  shoots  are  produced  the  second  year. 

Root.  -The  "beet"  itself  is,  for  the  most  part,  an  enlarged 
tap  root.  The  "crown"  of  the  beet  is  developed  from 
hypocotyl.  The  root  part  of  the  beet  may  be  distinguished 
from  the  hypocotyl  portion  (stem)  by  the  two  opposite,  longi- 
tudinal rows  of  secondary  roots  (Fig.  4).  The  tap  root 
extends  almost  straight  downward,  and  the  lower  portion  be- 
comes small  and  thread-like  and  commonly  reaches  a  depth 
of  4  feet  and  often  6  or  7  feet.  The  lateral  roots  and 
rootlets  are  very  abundant.  The  first  6  to  8  inches  of  the 
root,  however,  are  almost  free  of  side  roots.  The  upper 
laterals  are  the  largest  of  the  branch  roots  and  extend  farth- 
est in  the  soil,  spreading  almost  horizontally  2  to  3  feet.  The 
lower  laterals  are  more  vertical,  and  those  near  the  very  tip 
almost  parallel  with  the  tap  root. 

Stems. — The  upper  part  (crown)  of  the  sugar  beet  is 
hypocotyl,  i.e.,  stem.  This  is  a  very  much  shortened  fleshy 
stem  with  the  leaves  crowded  at  the  apex.  The  second  year, 
it  sends  up,  from  terminal  and  axillary  buds,  stout,  angular, 
branching  stems  to  a  height  of  3  or  4  feet;  the.se  stems  give  rise 
to  flowering  branches  (Fig.  119). 


302  BOTANY  OF  CROP  PLANTS 

Shape  and  Structiire  of  Beet  (Tap  Root  and  Hypocotyl) 

— Beet  Shape  and  Size,  and  Sugar  Content. — There  is  great 
variation  in  the  shape  and  size  of  sugar  beets.  Some  im- 
portance has  been  attached  to  the  correlation  between  sugar 
content  and  beet  shape  and  size.     This'relation,  however,  is 


'--1  .  i^^*ttVi 


Fig.    1 19. — Sugar  beet  plant  in  full  fruit. 


of  httle  signifuancc.  I'ritchard  has  recently  shown  that 
differences  in  the  size  and  sugar  content  of  individual  beet 
roots  are  fluctuations,  and  show  no  evidence  of  inheritance. 
It  is  true  that  unifonniLy  of  tyi)c  is  desirable,  but  any  aLLcni[)t 
to  judge  of  the  sugar  content  ol  an  individual  beet  by  the 


CHENOPODIACE^ 


303 


shape  and  size  is  useless.     Beets  with  a  large  crown  are 
undesirable. 

Anatomical  Structure  and  Sugar  Content. — The  researches 
of  a  number  of  European  investigators  have  shown  that  the 
anatomical  structure  of  the  sugar  beet  is  correlated  with 
sugar  content.  In  general,  beets  with  a  high  percentage  of 
sugar  have  a  finer  structure  than  those  with  a  low  percentage. 
A  cross  or  lengthwise  section  of  a  beet  shows  it  to  be  made  up, 
for  the  most  part,  of  a  ground  tissue  penetrated  by  groups  of 
vessels.     In  cross-section  (Fig.  120),  these  groups  of  vessels 


vascular 

-^mali-ceileci 
parench\jma 

larde-cejfed 
parencmma 

-ring  ofgrowih 

Diagrammatic  cross-section  of  sugar  beet  root. 


take  a  circular  form,  being  separated  from  each  other  by  par- 
enchyma tissue.  At  the  center  of  the  beet,  the  bundles  are 
close  together,  forming  the  so-called  "star. "  The  tissue  that 
separates  vessels  is  composed  of  two  kinds  of  parenchyma 
cells:  small  cells  surrovmding  the  vessels,  and  large  ones 
farther  removed.  The  smaller  parenchyma  cells  are  rich  in 
sugar,  while  the  larger  ones  are  principally  water  storage  cells, 
poor  in  sugar.  Hence,  beets  with  a  predominance  of  small- 
celled  parenchyma  are  richer  in  sugar  than  those  in  which 
large  water  storage  cells  predominate.    It  must  not  be  as- 


304 


BOTANY   OF   CROP   PLANTS 


sumed  from  this  that  it  would  be  possible  to  find  conspicuous 
differences  in  the  anatomical  structure  of  beets  varying  i  or 
2  per  cent,  in  sugar.  Furthermore,  a  certain  microscopical 
appearance  is  not  to  be  associated  with  a  given  sugar  content. 
Distribution  of  Sugar  in  the  Beet: — Fig.  121  shows  that 
the  beet  root  is  divided  into  various  zones  differing  as  to  their 


Fig.  121. — Diagram  show- 
ing distribution  of  sugar  in  an 
average  sugar  beet.  {After 
Molinari.) 


Fig.    122. — Sugar  beet    (Beta  vulgaris). 

A,  flowers  grouped  in  the  axil  of  a  bract; 

B,  cluster  of  flowers  which  fuse  to  form  a 
multiple  germ  beet  "seed." 


sugar  content.  The  sugar  content  decreases  from  a  point 
below  the  broadest  portion  of  the  root  to  the  crown  and  tip. 
Crossing  of  Vascular  Bundles  in  Crown. — In  a  longitudinal 
section  of  a  beet,  it  will  be  seen  that  there  is  a  crossing  of  the 
vascular  bundles  in  the  stem.     The  oldest  part  of  the  beet  is 


CHENOPODIACE^ 


305 


the  center;  new  rings  of  growth  are  placed  upon  these,  while 
the  new  leaves  come  from  the  center  of  the  crown.  Hence, 
there  is  a  crossing  of  the  older  and  younger  bundles  that  lead 
into  the  leaves. 

Rings  of  Growth. — The  rings  of  growth  vary  in  number,  de- 
pending upon  the  length  of  the  growing  season.  Ordinarily, 
six  to  ten  rings  complete  their  growth.  The  cambium  rings 
arise  in  the  pericycle,  each  remaining  active  but  for  a  short 
period  of  several  weeks. 

Leaves. — A  cluster  of  large  leaves  is  developed  from  the 
crown  of  the  beet  during  the  first  season.     The  oldest  leaves 


Fig.   123. 


-Beet   (Beta  vulgaris).     A,  floral  diagram;  B,  flower,  face  view. 
(A  after  Bessey.) 


are  on  the  outside,  the  youngest  toward  the  center.  Each 
leaf  has  a  long  petiole  which  broadens  out  at  the  base;  the 
blade  is  large  and  roughly  triangular  in  shape  at  the  base,  and 
longer  than  broad;  the  veins  are  prominent. 

Inflorescence. — The  inflorescences  are  loosely  spicate  and 
terminal.  The  flowers  are  arranged  along  an  axis,  singly  or 
in  dense,  sessile  clusters,  each  of  which  is  subtended  by  a  small 
bract.  Fig.  122,  A  shows  a  characteristic  cluster  of  beet 
flowers  in  the  axis  of  a  bract. 

Flowers. — Beet  flowers  are  perfect.     The  perianth  consists 


3o6  BOTANY  OF  CROP  PLANTS 

of  five  parts  united  below  to  the  base  of  the  ovary  (Figs.  123 
and  124).  There  are  five  stamens  opposite  to  and  partially 
attached  to  the  perianth  ring.  The  ovary  is  half-inferior, 
that  is,  partially  imbedded  in  the  flesh  of  the  receptacle,  one- 
celled  and  one-  to  three-seeded.  There  are  two  to  three 
short,  awl-shaped  stigmas,  united  at  the  base. 

Pollination  and  Fertilization. — The  beet  flower  is  protan- 
drous.  Shaw  has  shown  that  "self-fertilization "  (autogamy) 
does  not  take  place,  and  that  ''close 
fertilization"  (geitonogamy)  is  usu- 
ally ineffective.  He  has  also  demon- 
strated that  thrips  voluntarily  travel 
from  plant  to  plant,  and  positively 
assist  in  polKnation  of  beet  flowers. 
1^^  '  Bees  are  of  little  consequence  in  this 

Fig.  124.— Diagram  of     process.     Wind  is  the  chief  factor  in 
S  o"7:;ef  cuT °iLX     beet  pollen  dissemination. 
wise.  (After  Townsend  and        Finlt    and    Sccd. — The    ripened 

Riltue,  U.  S.  Dept.  Agri.)  .  ,       _  .       .     ,     j,     , 

ovary  of  each  flower  is  imbedded 
in  the  receptacle  and  the  base  of  the  perianth.  The 
fruit  is  hard  and  nut-like,  and  contains  a  single,  dark, 
smooth  seed.  The  beet  seed  of  the  market  is  frequently 
called  the  "seed  ball.''  The  "seed  ball"  usually  contains 
a  number  of  germs;  however,  in  some  cases  a  single  germ 
is  produced.  The  multiple-germ  beet  seed  arises  when  the 
flowers  are  in  clusters;  in  this  case,  the  parts  of  the  several 
flowers  stick  together  forming  a  several-seeded  mass,  the 
"seed  ball."  If  the  flower  stands  by  itself  on  the  stem,  a 
single-germ  beet  seed  is  produced.  The  single  flowers  are 
usually  located  at  points  on  the  stem  where  a  branch  arises. 
According  to  this,  a  highly  branched  inflorescence  will 
produce  a  greater  proportion  of  single  flowers. 

Tests  of  the  comparative  yields  of  beets  from  single-germ 


CHENOPODIACE^  307 

seeds  and  'multiple-germ  seeds  have  not  been  made.  Of 
course,  the  advantage  of  single-germ  seed  is  in  the  ehmina- 
tion,  to  a  large  extent,  of  "thinning."  Townsend  and 
Rittue  say  that  there  is  some  indication  that  plants  grown 
from  single-germ  seeds  produce  a  greater  number  of  single 
flowers  than  plants  from  multiple-germ  seeds.  It  must^be 
borne  in  mind  that  the  so-called  "beet  seed"  is  in  reality  a 
fruit,  that  a  multiple-germ  seed  consists  of  several  one- 
seeded  fruits,  and  a  single-germ  seed  of  one  one-seeded 
fruit. 

The  true  seed  is  kidney-shaped  and  about  the  size  of  a 
turnip  seed.  The  testa  is  thin,  dark  and  smooth.  The 
hilum  and  micropyle  are  basal.  The  white  and  floury  endo- 
sperm Hes  in  the  middle  of  the  seed,  surrounded  peripherally 
by  the  annular  embryo  (Fig.  117). 

Seed  Production. — The  beet  industry  in  the  United  States 
has  been  dependent  almost  wholly  upon  Germany  for  its 
supply  of  beet  seed.  However,  in  the  last  year  or  so,  con- 
siderable activity  has  been  manifested  in  the  growing  of  beet 
seed  at  home,  and  as  a  result,  we  are  now  growing  success- 
fully large  quantities  of  seed.  Since  the  beet  is  a  biennial, 
it  is  necessary  to  store  the  roots  of  the  first  year,  and  set 
them  out  the  following  season,  in  order  to  obtain  seed.  The 
"mother  beets"  may  be  tested  for  their  sugar  content  before 
planting,  and  only  those  which  show  the  desired  percentage 
of  sugar  set  out  for  seed  production.  The  testing  and 
selection  of  mother  plants  for  seed  has  resulted  in  the  striking 
improvement  of  beets. 

Germination,  and  the  Seedling.^The  primary  root  is  the 
first  to  appear.  Soon,  the  cotyledons  follow,  pushing  their 
way  above  ground.  The  seedhng  consists  of  a  very  short 
hypocotyl  which  scarcely  appears  above  ground,  two  rather 
fleshy,  glabrous,  short-petioled,  one-nerved  cotyledons,  and 


3o8 


BOTANY    OF    CROP   PLANTS 


a  tapering  primary  root  which  gives  off  a  few  red,  fibrous 
laterals. 

Types  of  Sugar  Beets. — There  are  two  well-known  and 
common  t3^pes  of  sugar  beets:  Kleinwanzlebener  and  Vil- 
morin.  The  Vilmorin  beet  is  of  French  origin,  and  as  com- 
pared with  the  Kleinwanzlebener,  a  German  beet,  is  more 
circular  in  cross-section,  smaller,  has  a  lighter  skin,  and  a 
much  smaller  top  of  leaves.  .The  secondary  root  lines  are 
straight  in  Vilmorin  beets,  and  spiral  in  Kleinwanzlebener 
beets.  The  percentages  of  sugar  in  the  two  types  are  about 
the  same.     The  tonnage  of  the  Vilmorin  is  smaller. 


Composition  of  Sugar  Beets.- 

made  by  Headden.^ 


-The  following  analyses  of  sugar  beets  were 


German 
beet,- 
grams 

Michigan 

beet, 
grams 

Colorado 
beet, 
grams 

Montana 
beet, 
grams 

74-SSO 
25-450 
16.600 
0.800 
o".  706 

813.000 
78.000 
22.000 
15.300 
0.701 
0.769 

673.000 
75.800 
24.200 
18.300 
0.820 
0.543 

479  300 

74.603 

25-370 

18.240 

2.680 

Water 

Dry  substance 

Sugar 

Total  ash 

Protein 

0.436 

Except  in  extreme  cases,  there  seems  to  be  little  support  for  the  statement 
that  the  greater  the  weight  the  less  the  sugar  content  of  the  beet.  The  com- 
position of  the  beet  is  afifected  by  age,  disease,  fertilizers,  insufficient  food 
supply,  light,  time  of  topping,  rainfall,  etc.  The  average  sugar  content  of 
American  grown  beets  is  about  15  per  cent.  Frequently,  the  yields  are  more 
than  20  tons,  and  the  sugar  content  17  to  20  per  cent. 

Manufacture  of  Sugar. — The  chief  use  of  sugar  beets  is  in 
the  manufacture  of  sugar.  The  beet  sugar  industry  has  made 
very  rapid  development  in  this  country.  In  the  making  of 
beet  sugar,  the  topped  beets  are  first  washed,  and  then  cut  by 

'  Colorado  Agri.  Exp.  Sta.  Bull.  183. 


CHENOPODIACE^  309 

machinery  into  narrow  strips  ("cossettes")-  These  strips 
are  placed  in  diffusion  vessels,  treated  with  water  at  a  tem- 
perature of  about  80  to  84°C.,  and  the  sugar  extracted  by 
diffusion.  The  juice  is  then  run  into  large  tanks,  where  milk 
of  lime  is  added  to  it.  The  liming  is  followed  by  the  intro- 
duction of  carbonic  acid,  which  precipitates  the  lime  as  a  car- 
bonate and  salts  of  the  acids  of  the  juice.  The  precipitate 
carries  down  most  of  the  impurities  in  the  juice.  When  the 
first  "  carbonatation "  process  is  about  completed,  the  juice 
is  heated  nearly  to  the  boiling  point,  filter-pressed,  and  the 
filtrate  lead  into  a  second  carbonatation  tank.  This  may  be 
followed  by  a  third  carbonatation.  The  purified  juice  is 
concentrated  by  boiling,  and  crystaUization  brought  about 
in  vacuum  evaporators.  The  material  that  comes  from  the 
vacuum  evaporators  is  a  mixture  of  crystals  and  molasses. 
This  mixture  ("masscuite")  is  placed  in  centrigufal  machines 
lined  with  fine  sieves;  here  the  molasses  is  driven  out  and  the 
sugar  retained.  The  sugar  is  next  fed  into  the  granulator, 
where  the  crystals  are  separated  from  each  other  during  the 
drying  process.  The  molasses  from  the  first  boiling  is  again 
boiled,  and  further  crystaUization  brought  about. 

By-products  of  Manufacture. — After  the  sugar  has  been 
removed  from  the  sliced  beets,  there  is  left  a  substance  known 
as  "beet  pulp."  This  is  a  valued  stock  food.  However,  it 
cannot  be  made  the  sole  ration  of  an  animal,  as  it  is  deficient 
in  nitrogenous  food  materials.  Beet  pulp  is  sometimes  dried, 
mixed  with  molasses,  and  fed  to  dairy  cows.  Molasses  from 
the  second  boiling  is  also  valued  as  a  stock  food.  The  refuse 
that  accumulates  in  the  purification  process  is  sometimes 
employed  as  a  fertihzer.  It  has  been  demonstrated  that  it  is 
possible  to  manufacture  fusel  oil,  alcohol,  rum,  and  vinegar 
from  the  refuse  molasses.  There  are  many  other  ways  of 
utiHzing  sugar-beet  molasses, 


3IO  BOTANY   OP   CROP   PLANTS 

COMMON  GARDEN  BEET 

The  botanical  characters  of  the  garden  beet  are  very  similar 
to  those  of  sugar  beet.  As  is  well  known,  however,  they  are 
not  so  rich  in  sugar  and  differ  from  them  in  color,  shape,  and 
edible  quahties. 

Types. — As  to  color,  there  are  two  main  groups  of  garden 
beets:  (i)  Flesh  red  (Early  Blood  Turnip,  Eclipse,  Egyptian, 
Detroit,  Dark  Red);  and,  (2)  Flesh  yellow  (Early  Yellow 


Fig.   125. — Percentage  of  the  world's  supply  of  beet  sugar  (raw)  produced  in 
the  different  countries,  campaign  of  1913-14. 

Turnip,  Golden  Globe) .     Goff  divides  garden  beets  into  four 
types  as  to  shape : 

1.  Root  oblate  or  top-shaped  (Early  Blood  Turnip, 
Eclipse,  Egyptian,  etc.). 

2.  Root  half  long  (Victoria). 

3 .  Root  oval  (Strasbourg  Pear-shaped,  Dell's  Black-leafed) . 

4.  Root  long-conical  (Long  Blood,  Long  Yellow). 

Uses. — Garden  beets  are  mostly  for  table  use.  The  flavor 
of  early  varieties  is  more  deHcate  than  that  in  later  maturing 
ones.  The  roots  are  boiled,  pickled,  or  mixed  in  salads. 
Considerable  quantitites  are  canned,  and  in  some  cases  the 
common  garden  sorts  are  used  for  stock  food. 


r   '< 

\                lo 

1    i<«  . 

•  ■•'•  -/.f}-^ 

■  ■    A   • 

-^ 


- 

J 

2 

s 

1 

z 
< 

2 

^ 

■ 

10 

3 

1 

c^ 

J 

iJ^^I 

"  O 

X  < 

=3  LJ 

=  a: 

S  O 

e=  < 


< 

^1 

Siisl! 

S 
^ 

g 

3 

lll-plll- 

i 

53ill^Jl 

312  BOTANY    OF    CROP    PLANTS 

CHARD 

The  edible  "leaf  beets"  go  under  various  names:  Spinach 
beet,  sea-kale  beet.  Swiss  chard,  silver  beet,  chard,  and 
Bcla   cvcla.     The    tlower>   and    fruit   are   like    those   of   the 


E9i 

Ub^^^^^^H 

HIHI 

^m7>j^Ej| 

r  "^^19 

H^H 

1 ,  ^^S 

'^^ 

i^Si 

^^B^t'^r  >S 

^■'Wh 

^^B   ^'Hb 

IP 

Edf 

^^'  (^^^1 

^^B  '^'^ 

W  '^ 

^^^^^H 

^^^^Lv'a 

Sf  ^^H 

1 

Fk;.    I  J7. -Chard  or  IlmI  larl  (Beta  vulj^ari.). 

common  beet.  Cultivation  has  changed  its  habit  of  growth, 
however,  such  that  leaves,  instead  of  roots  have  become 
developed. 


CHENOPODIACE^ 


313 


The  plant  is  a  biennial  with  a  somewhat  branched  and 
thickened,  but  not  fleshy,  root  system.  The  leaves  are 
clustered  at  the  surface  of  the  ground  (Fig.  127);  they  bear 
large,  thick  leaf  stalks  and  large  blades.  The  leaf  stalks 
are  often  as  much  as  2  feet  long  and  i  to  3  inches  thick. 

The  chief  variety  grown  in  this  country  is  Lucullus,  one 
in  which  the  leaves  are  heavily  crumpled  or  "savoyed." 
Swiss  chard  is  a  variety  with  dark,  green  leaves.  There 
are  forms  of  chard  with  white,  red  or  pink  leaf  stalks. 

Chard  is  grown  for  its  tender  leaves  and  petioles.  The 
leaves  are  boiled  Hke  spinach,  and  the  petioles  are  served  like 
asparagus. 

MANGEL-WURZELS  OR  MANGELS       1 

To  this  group  belong  the  stock-feeding  varieties  of  Beta  vul- 
garis. The  botanical  characters  are  very  similar  to  those 
given  for  the  sugar  beet. 


-Types  of   mangels.     A,   long;   B,   intermediate;   C,   tankard;    D' 
globe.      (After  Percival.) 


Types. — As  to  shape,  there  are. four  well-recognized  types 
of  mangels  (Fig.  128): 

1.  Glohe. — In  these  varieties,  the  roots  are  globular,  and 
project  above  ground  for  more  than  half  their  length  (Yellow 
Globe,  Orange  Globe). 

2.  Tankard. — Varieties  of  this  type  have  roots  which  are 


314  BOTANY  OF  CROP  PLANTS 

almost  cylindrical,  and  narrow  abruptly  at  both  ends.     The 
roots  are  comparatively  small  (Golden  Tankard). 

3.  Oval  or  ^^ Intermediate.'^ — The  roots  in  these  are  oval, 
and  intermediate  in  shape  between  globe  and  long  varieties. 
They  vary  in  color  (Giant  Intermediate). 

4.  Long. — Roots  of  this  type  are  several  times  longer  than 
broad  and  project  above  the  soil  for  a  considerable  propor- 
tion of  their  length.  They  are  heavy  yielders.  Both  red 
and  yellow-skinned  varieties  (Long  Red,  Long  Yellow)  occur. 
The  ox-horn  varieties  have  long  twisted  and  horn-Hke  roots. 

Composition  and  Uses. — I'he  mangels  vary  in  sugar  con- 
tent from  3  to  8  per  cent.,  the  Golden  Tankard  and  Globes 
having  the  highest  percentage.  Long  varieties  are  relatively 
low  in  sugar  content  but  produce  a  greater  tonnage  per  acre. 
The  water  content  varies  from  85  to  92  per  cent.  Mangels 
are  being  extensively  grown  for  stock  food.  They  are 
one  of  the  most  important  root  crops.  The  root  crops 
include  all  plants  whose  underground  vegetative  parts,  such 
as  rootstocks  or  roots,  are  utiHzed.  Bulbs  and  tubers, 
however,  are  usually  excluded.  Examples  of  root  crops  are 
beets,  mangels,  turnips,  carrots,  rutabagas,  sweet  potatoes, 
and  artichokes.  Root  crops  are  used  for  human  food  and 
also  for  forage.  It  must  be  kept  in  mind  that  all  "root 
crops"  are  not  wholly  roots,  morphologically,  but  that  in 
some,  such  as  the  carrot,  turnip,  rutabaga,  mangel  and  beet, 
the  lower  two-thirds  or  more  of  the  underground  part  is 
root,  the  remainder  stem  ("crown").  Practically  all 
root  crops  are  best  adapted  to  localities  with  a  cool  growing 
season. 

References 

GoFF,  E.  S.:  Vegetables:  Garden  Beet.     6th  Ann.  Kept.  N.  Y.  Agr.  Exp. 

Sta.,  120-132,  1887. 
Kinney,  L.  F.:  Spinach.    R.  I.  Agr.  Exp.  Sta.  Bull.  41:  99-131,  1896. 


CHENOPODIACE^  315 

Pritchard,  F.  J.:  Some   Recent  Investigations   in   Sugar-beet   Breeding. 

Bot.  Gaz.,  62  :  425-465,  1916. 
RtJGGEBERG,   H. :  Beitrage   zur   Anatomic   der   Zuckerriibe.     Mitt.   Kaiser 

Wilhelms  Inst.  f.  Landw.  Bromberg,  4:  399-415,  1912. 
Shaw,  G.  H.:  Thrips  as  Pollinators  of  Beet  Flowers.     U.  S.  Dept.  Agr. 

Bull.  104:  1-12,  1914. 
TowNSEND,  C.  O.,  and  Rittue,  E.  C.:  The  Development  of  Single-germ  Beet 

Seed.     U.  S.  Dept.  Agr.  Bur.  Plant  Ind.  Bull.  73:  1-23,  1905. 
TowNSEND,  C.  O.:  Single-germ  Beet  Seed.     Jour.  Hered.,  6:  351-354,  iQ^S- 


CHAPTER  XXIV 
GROSSULARIACE^  (Gooseberry  Family) 

There  is  but  one  genus — Ribes — in  this  family.     It  includes 
the  gooseberries  and  currants. 

Stems. — Gooseberries  and  currants  are  erect  or  procum- 
bent shrubs.  The  stems  of  gooseberries  are  armed  with 
spines  and  prickles,  while  currants  have  neither  of  these 
present  on  the  stems.  The  spines  and  prickles  of  gooseberries 
are  stem  emergences,  thus  differing  from  those  of  certain 
plums  and  thornapples,  which  are  reduced  branches.  Some 
cultivated  varieties  of  gooseberries  are  almost  thornless. 
In  gooseberries  the  fruit  is  borne  on  one-year-old  wood  and 
from  spurs  (short  branches)  on  older  wood.  As  a  rule,  these 
spurs  only  bear  well  for  the  first  two  or  three  years.  Black 
currants  produce  the  most  fruit  on  wood  that  is  one  year  old, 
while  red  and  white  currants  produce  fruit  most  abundantly 
on  spurs  that  arise  from  wood  two  or  more  years  old.  When 
the  canes  ("stems")  reach  an  age  of  four  or  five  years  their 
yield  decreases,  and  hence  it  is  the  practice  to  prune  out  old 
canes,  and  keep  a  supply  of  new  ones  coming  on.  The  cut- 
ting back  of  old  canes  not  only  induces  the  formation  of 
fruit  spurs,  but  new  canes  as  well.  Propagation  of  both 
gooseberries  and  currants  may  be  made  by  stem  cuttings; 
gooseberries  are  also  propagated  by  layering,  and  occasionally 
from  root  cuttings.  In  layering,  the  branches  are  bent  over 
and  covered  with  earth;  after  the  buried  stems  take  root, 
the  newly  rooted  part  is  severed  from  the  parent  plant. 
316 


GROSSULARIACE^ 


317 


Leaves. — The  leaves  are  alternate,  palmately  lobed,  often 
resinous-glandular  or  viscid.  Stipules  are  wanting  or  pres- 
ent. In  all  gooseberries  and  most  currants,  the  leaves  are 
plicate  (Fig.  loi)  in  the  bud.  In  a  few  cases,  as  the  golden 
currant  {Ribes  aureum),  they  are  convolute  (Fig.  loi). 

Inflorescence  and  Flowers. — Currants  and  gooseberries 
usually  have  a  typical  racemose  type  of  inflorescence;  rarely 
the  flowers  are  solitary.     Each  pedicel  is  subtended  by  a 


Fig.  129. — A,  flower  of  red  currant  (Ribes  rubrum)  in  lengthwise  section; 
B,  flower  of  golden  currant  (Ribes  aureum).  The  portion  designated  calyx- 
tube  is  in  reality  toral  tube.     {A  after  Sargent.) 

bract  and  usually  also  bears  two  bractlets  at  about  the 
middle.  The  flowers  are  perfect,  regular,  with  calyx  and 
corolla  both  present  and  well  differentiated  (Fig.  129).  The 
receptacle  (torus)  is  cup-shaped  and  surrounds  the  carpels 
(Fig.  130).  The  calyx  is  divided  into  four  or  five  lobes, 
often  colored.  There  are  four  or  five  very  small  petals, 
scale-like  and  alternating  with  the  calyx  lobes;  the  petals 
are  free,  and  inserted  on  the  throat  of  the  calyx  tube.     The 


3l8  BOTANY  OF  CROP  PLANTS 

stamens  are  of  the  same  number  as  petals,  and  are  usually 
included,  and  attached  to  the  perianth.  The  inferior  ovary 
is  one-celled  with  two  parietal  placentae,  each  bearing 
numerous  ovules;  two  more  or  less  united  styles  are  present. 

Pollination. — Gooseberries  and  currants  are  cross-polli- 
nated, for  the  most  part.  Insects  are  the  chief  agents  in 
pollination. 

The  Mature  Fruit. — The  fruit  of  the  currant  and  goose- 
berry has  been  regarded  as  a  berry;  that  is,  a  true  fruit 


vdscular  bundle 
Of  receptacle 


vascular  bundle 


LSC 

ofc 


Fig.  130. — Diagrammatic  cross-section  of  Ribes  flower  prior  to  fertiliza- 
tion. Note  that  carpel  tissue  is  surrounded  by  receptacle  tissue,  as  is  evi- 
denced by  the  two  distinct  sets  of  vascular  bundles.  The  fleshy  part  of  the 
Ribes  fruit  is  thus  seen  to  be  composed  of  receptacle  tissue  for  the  most  part ; 
hence  the  fruit  is  not  a  berry,  morphologically,  but  rather  pome-like.  {Dia- 
gram from  microscopic  section  and  data  furnished  by  E.  J.  Kraus.) 

possessing  numerous  seeds  more  or  less  imbedded  in  a  fleshy 
endocarp  and  mesocarp.  Recent,  unpublished  work  of 
Kraus  establishes  the  fact  that  the  fruit  is  in  reaHty  pome- 
like in  its  structure.  A  cross-section  through  the  base  of 
the  flower  or  through  the  fruit  shows  two  distinct  sets  of 
vascular  bundles  (Fig.  130),  the  outer  belonging  to  the  re- 


GROSSULARIACEiE  319 

ceptacle  and  leading  to  the  sepals,  petals  and  stamens,  the 
inner  to  the  carpels.  Thus  it  is  seen  that  a  large  portion  of 
the  flesh  of  the  Ribes  fruit  is  toral  and  not  carpellary. 
Toral  or  receptacle  tissue  and  carpellary  tissue  imperceptibly 
grade  into  each  other. 

Seeds. — The  seeds  are  small,  and  slightly  flattened  on  one 
side.  The  outer  layer  of  the  seed  coat  is  comparatively  thick 
and  gelatinous  and  the  inner  layer  is  thin.  There  is  an 
abundance  of  endosperm.  A  minute  embryo  occurs  at  the 
base  of  the  seed. 


Geographical. — There  are  about  100  species  of  the  genus  Ribes.  These  arc, 
for  the  most  part,  natives  of  temperate  Europe,  Asia,  North  America  and  the 
Andes  of  South  America. 


Key  to  Important  Species  of  Genus  Ribes 

Stems  with  one  to  three  thorns  below  the  clusters  of  leaves,  often  with  nu- 
merous scattered  prickles  on  the  branches,  sometimes  upon  the  fruit 
also.     Leaves  plaited  in  the  bud  (Fig.  loi)  (Gooseberries). 
Fruit  unarmed  and  smooth;  spines  on  the  branches  generally  solitary 
(sometimes  triple)  and  slender.     R.  oxyacanthoides  (common  gooseberry) . 
Fruit  armed  with  prickles,  or  rough   and  glandular-hairy;  spines  on  the 
branches    usually    three    together,   stout.     R.    grossularia    (European 
gooseberry). 
Thornless  and  pricklel ess;  leaves  plaited  in  bud  (Fig.  loi);  racemes  few-  to 
many-flowered  (Currants). 
Torus  dilated  immediately  above  the  ovary. 

Leaves  without  resinous  dots  beneath;  fruit  red  or  light.     R.  rubrum 

(garden  currant). 
Leaves  with  resinous  dots  beneath;  fruit  black.     R.  nigrum  (Euro- 
pean black  currant). 
Torus    prolonged    above    the    ovary    into    a   campanulate,  cylindrical 
tube.     R.  americanum  (American  black  currant). 
Thornless  and  prickleless;  leaves  convolute  in  the  bud  (Fig.  loi);  racemes 
several  flowered;  torus  above  much  elongated,  bright  yellow.     R.  atireum 
(Missouri,  flowering,  golden,  or  Buffalo  currant). 


320  BOTANY   OF   CROP   PLANTS 


CURRANTS 


Species.- — There  are  four  principal  species  of  currants  in 
American  currant  culture. 

(i)  Rihes  rubrum  {R.  vulgare)  includes  all  our  red  and 
white  varieties,  and  is  the  most  important  species  commer- 
cially. The  leaves  are  hairy  at  first,  but  become  smooth  with 
age.  The  small,  greenish-yellow  or  purplish  flowers  are  in 
drooping  racemes.  The  fruit  varies  in  color;  it  may  be 
bright  red,  yellowish,  white,  or  striped.  This  species  is  found 
growing  wild  from  New  England  to  Minnesota  and  north- 
ward; also  in  Europe  and  Asia.  Commercially,  its  culture  is 
restricted  to  northern  latitudes.  Important  varieties  are 
Victoria,  Red  Dutch,  Cherry,  Versaillaise,  Fay,  Prince 
Albert,  and  White  Grape. 

(2)  Rihes  nigrum,  the  European  black  currant,  is  but  little 
cultivated  in  America.  It  differs  from  the  preceding  in 
several  respects:  the  lower  surfaces  of  leaves  are  covered  with 
yellow,  resinous  dots,  and  the  fruit  is  black.  The  greenish- 
white  flowers  are  in  drooping  racemes,  and  the  fruit  and 
toral  tube  are  both  hairy  and  resinous-dotted.  This  currant 
is  a  native  of  middle  and  northeast  Europe,  through  northern 
Asia  to  Manchuria  and  northern  China. 

(3)  Rihes  americanum,  the  native  wild  black  currant  of 
America,  is  not  cultivated  to  any  extent.  The  plant  has  a 
spreading  habit.  As  in  the  European  black  currant,  the 
lower  surfaces  of  leaves  are  resinous-dotted,  and  the  fruit  is 
black  in  color,  but  it  differs  from  the  European  species  in  that 
the  toral  tube  and  fruit  are  not  resinous.  It  is  distributed 
from  Nova  Scotia  and  New  England  south  to  Virginia  and 
westward  to  Colorado  and  Manitoba. 

(4)  Rihes  aureum  is  the  chief  American  flowering  currant. 
It  is  cultivated  principally  as  an  ornamental  shrub,  but  also 


GROSSULARIACEiE  321 

for  its  fruit.  The  wedge-shaped  leaves  are  three-lobed, 
smooth,  and  resinous  when  young.  The  short  inflorescence 
is  very  leafy.  The  most  characteristic  feature  of  the  plant  is 
its  flowers  (Fig.  129,  B)  which  have  a  long,  tubular,  yellow 
toral  tube,  and  small  reddish  petals.  The  fruit  is  dark 
brown  or  black.  The  species  is  native  to  the  Mississippi 
Valley,  and  westward  to  the  Rocky  Mountains.  Important 
varieties  are  Crandall,  Deseret  and  Jelly. 

Uses. — Currants  are  made  use  of  for  jelly,  pies,  sauce,  and 
wine. 

GOOSEBERRIES 

Species. — The  cultivated  gooseberries  belong  to  two 
species:  Ribes  grossularia,  of  Europe,  and  Ribes  oxyacan- 
thoides  {R.  hirtellum),  of  America.  European  gooseberries, 
as  compared  with  American  sorts,  are  less  productive,  less 
hardy,  not  so  easily  propagated  by  cuttings,  have  a  thicker 
skin,  a  poorer  quality  of  fruit  and  are  less  resistant  to  the 
common  gooseberry  mildew  {Sphcerotheca  mors-uvcB). 

Ribes  grossularia. — This  is  a  robust  plant,  bearing  large 
thorns,  usually  in  threes.  The  leaves  are  shining  and 
pubescent.  The  flowers  have  a  pubescent  toral  tube  and 
fruit.  The  large  berry  is  rough,  hairy  or  prickly,  red,  green- 
ish, or  yellowish  in  color.  The  species  is  a  native  of 
Europe,  northern  Africa  and  western  Asia. 

Ribes  oxyacanthoides. — The  American  gooseberry  is  not 
as  robust  as  the  preceding.  The  thorns,  sometimes  in 
threes,  sometimes  single,  are  much  more  slender,  and  in 
some  varieties  may  be  entirely  wanting.  The  leaves  are 
shining  and  finely  hairy.  The  greenish  or  purplish  flowers 
have  a  smooth  or  hairy  toral  tube  and  a  smooth  fruit.  The 
small  berry  is  perfectly  smooth,  and  reddish  in  color.  Ribes 
oxyacanthoides  grows  from  Newfoundland  to  New  Jersey 


32  2  BOTANY  OF  CROP  PLANTS 

and  westward  to  the  Rocky  Mountains.  Important  varie- 
ties are  Downing,  Pale  Red,  Red  Jacket,  Champion  and 
Pearl.  There  are  hybrids  between  the  American  and 
European  species. 

Uses. — Gooseberries  are  used  either  green  or  ripe.     They 
are  made  into  pies,  jelly,  wine,  and  stewed  or  canned. 


CHAPTER  XXV 


CRUCIFER^  (Mustard  Family) 


This  family  is  of  world-wide  distribution.  There  are  in 
the  neighborhood  of  2,000  species  in  180  genera.  The  largest 
number  of  genera  and  species  is  found  in  southern  FAirope 
and  Asia  Minor.  They  are 
found  from  low  to  high  latitudes 
and  from  low  to  high  altitudes. 

Many  of  the  genera  yield  crop 
plants,  such  as  cabbage,  turnip, 
rutabaga,  rape,  black  mustard, 
white  mustard,  radish,  water 
cress  and  horse  radish,  while  a 
number  of  genera  include  per- 
nicious weeds,  such  as  penny 
cress,  wild  mustard  or  charlock, 
shepherds  purse,  false  flax,  and 
tansy  mustard. 

Stems,  Leaves. — ]\rost  mus- 
tards are  herbaceous;  a  few  are 
woody.  The  sap  is  usually 
watery  and  acrid.  The  leaves 
are  alternate,  simple,  and  vari- 
ously lobed  or  dissected.  The 
sti[)ules  are  wanting. 

Inflorescence  and  Flowers.— The   predominant    t\[)e   of 
injloresccnce  is  a   terminal  raceme;   rarely   the   [lowers  are 
solitary  at  the  end  of  a  scape.     The  mustard  jloiver  is  char- 
323 


Cruciferai.  Floral 
diagram  above;  flower  in  median 
longitudinal  section  below. 


324 


BOTANY    OF    CROP    PLANTS 


acteristic  (Fig.  131).  It  is  perfect  and  regular  with  four 
sepals,  four  petals,  six  stamens  (two  short  and  four  long), 
and  a  two-celled  ovary.     The  four  sepals  are  entirely  dis- 


pjf.  j_j2. — Common  garden  radish  (Raphanus  sativus).  In  flower,  on 
right;  and  in  fruit,  on  left.  Note  the  characteristic  racemose  inflorescence 
with  flowers  at  the  apex  and  fruit  at  the  base. 

tinct,  but  often  overlapping;  the  two  outer  are  narrow,  and 
the  two  inner  may  be  narrow  also,  but  often  are  distinguished 
from  the  outer  by  being  concave  or  saccate  at  the  base;  they 


CRUCIFERiE 


325 


are  in  two  distinct  whorls.  The  four  petals  are  so  arranged 
that  when  one  looks  at  the  face  of  the  flower,  it  has  the 
appearance  of  a  Greek  cross,  hence  the  name  Cruciferae 
(Latin,  crux,  cross,  +  fera,  to  bear).  The  petals,  as  a  rule, 
are  clawed,  that  is,  have  a  narrow  or  stalk- 
like base  at  the  tip  of  which  is  a  broader 
blade;  they  are  similar  as  to  size  and  shape. 
Nectar  glands  are  frequently  found  at  the 
base  of  petals.  The  six  stamens  are  in  two 
whorls,  the  outer  two  opposite  each  other 
and  opposite  the  two  sepals  of  the  inner 
whorl,  and  with  short  filaments,  the  inner 
four  stamens  opposite  the  petals  and  with 
long  filaments;  the  anthers  are  two-loculed 
(rarely  one),  and  longitudinally  dehiscent. 
The  single  pistil  is  superior,  usually  sessile, 
compound,  and  has  a  single  style  with  a 
more  or  less  two-lobed  or  disk-shaped  stigma; 
the  ovules  are  attached  to  two  parietal 
placentas,  which  are  connected  by  a  "false" 
partition,  an  outgrowth  of  the  placentas 
themselves. 

Fruit. — The  ovary  develops  into  a  pod-hke 
fruit  (Fig.  133),  which  is  termed  a  silique  pic.  133.— Fruit 
(Brassica)  when  long  and  slender,  and  a  of  cabbage  (Bras- 
silicle  (Bursa)  when  short  and  broad.  The  tata)°.  ^^^^!\xter- 
sides  (valves)  of  the  fruit  separate  at  dehis-  ^.^^''  ^'  cross-sec- 
cence,  leaving  the  two  placentas  and  false 
partition.  In  a  few  genera  {Raphanus,  radish),  the  fruit  is 
indehiscent. 

Seeds. — The  seeds  are  usually  many,  attached  to  both 
sides  of  the  partition,  and  have  a  mucilaginous  testa;  the 
endosperm  is  lacking;  cotyledons  are  incumbent  (with  their 


326       .  ■      BOTANY  OP  CROP  PLANTS 

back  against  the  hypocotyl),  accumbent  (margins  folded 
against  the  hypocotyl),  or  conduplicate  (folded  upon  them- 
selves lengthwise). 

The  seeds  of  mustards,  like  those  of  grasses  and  composites, 
are  short-Kved,  as  compared  with  those  of  the  mallow  family, 
potato  family  and  pea  family.  Longevity  of  seeds  is  due  to 
a  number  of  factors,  chief  of  which  is  impermeability  of  the 
seed  coats  to  water  and  oxygen.  Seeds  with  permeable  coats 
are  more  sensitive  to  moisture  and  temperature  changes  than 
are  those  with  impermeable  ones.  When  moisture  is  absorbed 
by  the  seed  its  rate  of  respiration  is  increased,  and  hence  its 
vitaHty  reduced.  This  may  be  an  important  factor  in 
shortening  the  Ufa  of  the  seed. 

Closely  Related  Families. — Members  of  the  mustard  family  may  be  mis- 
taken for  those  of  the  poppy  family  (PapMeracece)  or  caper  family  {Cappari- 
dacece),  both  of  which  are  closely  related.  The  poppies  have  perfect  flowers, 
usually  with  two  early  deciduous  sepals,  while  capers  are  distinguished  from 
mustards  by  the  six  approximately  equal  stamens  and  by  the  one-celled 
capsule. 

Key  to  Principal  Genera 

Pod  indehiscent,  Raphanus  (radish). 
Pod  dehiscent  into  two  valves. 
Pod  a  silique,  at  least  twice  as  long  as  wide. 
Leaves  dissected,  Sophia  (tansy  mustard). 
Leaves  broadly-lobed. 

Silique  beaked  by  a  persistent  style);  seeds  in  one   row,    Brassica 
(cabbage,  turnip,  rutabaga,  rape,  black  mustard  and  white  mustard). 
Silique  beakless;  seeds  in  two  rows,  Radicula  (water  cress  and  horse 
radish) . 
Pod  rarely  more  than  twice  as  long  as  broad. 

Silique  not  flattened,  nearly  circular  in  cross-section,  Camelina  (false 

flax). 
Silique  flattened. 

Silique  elliptic  or  oval,  Lepidium  (penny  cress). 
Silique  triangular-obovate  or  obcordate. 

Basal  (radical)  leaves  pinnatifid,  Capsella  (shepherd's  purse). 
Basal  leaves  entire  or  merely  toothed,  Thlaspi  (penny  cress). 


CRUCIFERiE  327 

BRASSICA 

Generic  Description. — This  genus  includes  annual  (black 
mustard),  biennial  (turnip),  or  perennial  (cabbages  under 
their  natural  conditions)  herbs.  The  root  system  may  be 
fleshy  (turnip),  or  rather  woody  and  solid  (cabbages).  The 
basal  (radical)  leaves  are  frequently  pinnatifid,  while  those 
of 'the  stem  (cauline)  are  entire,  dentate,  or  broadly  lobed. 
The  large,  yellow  flowers  are  in  elongated  racemes.  The 
sepals,  petals,  and  stamens  are  as  described  for  the  family. 
The  silique  (Fig.  133)  is  elongated,  sessile,  terete  or  four- 
sided,  and  tipped  with  an  indehiscent,  conic,  usually  one- 
seeded  beak;  the  valves  are  convex,  one-  to  three-nerved, 
the  lateral  ones  often  flexuous;  the  septum  (partition)  is 
membranous  or  spongy;  at  the  tip  of  the,  sihque  is  a  short  or 
elongated  style  tipped  by  a  truncate  or  two-lobed  stigma. 
The  seeds  are  in  one  row  in  each  cell. 

Pollination.— Representatives  of  rtie.  genus  are  for  the  most 
part  insect  pollinated.  It  appears  that  both  self-  and  cross- 
pollination  takes  place. 

Seedling. — At  germination  of  the  seed,  the  cotyledons  are 
brought  above  ground.  In  all  representatives  of  the  genus, 
the  cotyledons  are  emarginate  (notched  at  apex),  unequal 
in  size,  and  three-nerved  at  the  base. 

Geographical.^— There  are  about  80  species  in  the  genus  Brassica,  chiefly 
occurring  about  the  Mediterranean  region;  some  are  now  cultivated,  however, 
in  boreal  and  subtropical  regions  of  Europe,  Asia,  Africa,  and  North  and  South 
America.     None  of  the  Brassicas  are  native  of  America  or  Australia. 

Key  to  Principal  Species  of  Genus  Brassica 

Leaves  of  flowering  stem  not  clasping;  annuals;  sepals  spreading. 

Seeds  small,  reddish-brown;  valves  of  silique  one-nerved,  B.  nigra  (black 

mustard). 
Seeds  large,  pale  yellow;  valves  of  silique  three-nerved,  B.  alba  (whit? 

mustard). 


328  BOTANY  OF  CROP  PLANTS 

Leaves  of  flowering  stem  somewhat  clasping;  biennials;  sepals  erect. 
Roots  swollen  and  fleshy. 

Young  leaves  glaucous;  a  distinct  short  stem  on  upper  part  of  root,  B. 

campestris  (rutabaga  or  Swede  turnip). 
Young  leaves  grass-green;  no  distinct  short  stem  on  upper  part  of  root,  B. 
rapa  (turnip). 
Roots  not  fleshy. 

Young  foliage  covered  with  a  few  hairs,  B.  napus  (rape). 
Young  foliage  smooth,  B.oleracea  (cabbages,  etc.). 

BR/^SSICA  OLERACEA  (Cabbages,  etc.) 

Wild  Cabbage. — This  is  the  parent  of  the  various  forms 
of  cultivated  cabbage.     It  grows  wild  along  the  coasts  of 


Fig.   134. — Wild  cabbage.     (After  Bailey.) 

England  and  Wales,  Channel  Island,  and  western  and  south- 
ern Europe.  It  is  a  stout  perennial  or  biennial  from  a  tough 
and  woody  root.  The  stem  is  branching  and  attains  a 
height  of  I  to  2  feet  (Fig.  134).  The  lower  leaves  are  stalked, 
lyrate  or  pinnatifid,  entire,  and  broad,  while  the  upper  ones 
are  sessile  and  much  smaller.  There  is  no  tendency  to  form 
heads  in  the  wild  form.  The  flowers  are  in  elongated 
racemes  and  are  rather  large,  about  ^i  to  i  inch  in  diameter, 
and  of  a  pale  yellow  color.  The  fruit  is  a  smooth  silique 
often  3  or  4  inches  long. 


CRUCIFER^  329 

Cultivated  Types  of  Cabbages. — A  number  of  types  have 
arisen,  probably  as  mutants,  from  the  native  wild  cabbage. 
The  modifications  concern  the  stem  as  in  kohlrabi,  the  foliage 
as  in  kale,  head  cabbage,  and  Brussels  sprouts,  and  inflores- 
cence, as  in  broccoli  and  cauliflower.  The  characteristic 
differences  between  these  are  shown  in  the  following  key: 

Key  to  Cultivated  Types  of  Cabbages 

Stem  of  first  year  elongated. 

Stem  branched  and  leafy;  plant  much  resembling  wild  cabbage  (Fig.  135), 

B.  oleracea  var.  viridis  (kales  and  coUard). 
Stem  unbranched,  the  axillary  buds  developing  into  small  heads  (Fig.  136), 
B.  oleracea  var.  gemmifera  (Brussels  sprouts). 


Fig.    135. — Kale    (Brassica   oleracea       Fig.  136. — Brussels  sprouts  (Brassica 
viridis).     (After  Vilmorin.)  oleracea  gemmifera). 

Stem  of  first  year  short. 
First-year  stem  forming  a  "head"  (Fig.  137),   B.  oleracea  var.  capitata 

(common  cabbage). 
First-year  stem  not  forming  a  "head." 


330  BOTANY  OF  CROP  PLANTS 

Turnip-like  stem  which  stands  mostly  above  ground.     (Fig.   138),  B 

oleracea  var.  caulo-rapa  (kohlrabi). 
Stem  not    turnip-like,    leafy  below,  inflorescence  partially  developing 

first  season  (Fig.  139),  B.  oleracea  var.  botryiis  (cauliflower,  broccoli). 

BRASSICA  OLERACEA  VAR.  VIRIDIS  (Fig.  13s) 

The  members  of  this  group  resemble  very  much  the  wild 
form  of  cabbage.  The  terminal  and  lateral  buds  elongate 
during  the  first  season,  giving  the  plant  a  branching  habit. 
Forms  of  this  variety  are  known  as  kale,  borecole,  marrow 
cabbage,  or  collard.  Collards  are  grown  in  the  South  par- 
ticularly. This  southern  form  is  known  as  the  Georgia 
collard.  Marrow  cabbage  or  marrow  kale  is  a  broad-leaved 
form.  There  are  a  number  of  kales  with  finely  dissected 
leaves;  among  such  are  the  well-known  Scotch  kales,  rather 
common  market  sorts.  The  tree  kales  have  straight,  stiff 
and  strong  stems  often  3  or  4  feet  tall;  the  dwarf  kales  are 
lower  and  close  to  the  ground.  Dwarf  Green  Scotch  Kale 
is  the  most  common  sort  grown  in  the  Norfolk  truck-garden- 
ing area.  Thousand-headed  kale  is  a  very  large,  highly 
branching  form.  The  large-leaved  kales,  such  as  marrow 
kale  and  thousand-headed  kale,  are  used  as  stock  food.  The 
finer-leaved  varieties  are  used  as  a  boiled  green  vegetable. 

Unlike  their  close  relatives,  Brussels  sprouts,  head  cabbage, 
kohlrabi  and  cauHflower,  kale  and  collard  will  endure  the 
heat  and  drought  of  summer,  and  kale,  at  least,  will  stand 
considerable  freezing. 

BRASSICA  OLERACEA  VAR.  GEMMIFERA  (Brussels  sprouts)  (Fig.  136) 

'Here  belong  those  cabbages  in  which  the  axillary  buds 
develop  into  small  heads  or  "sprouts."  These  are  formed 
in  the  axils  of  leaves.  The  main  stem  is  elongated  and 
unbranched.  The  first  "sprouts"  to  appear  are  those  at  the 
base  of  the  stem,  subsequent  ones  appearing  in  order  from 


CRUCIFER^ 


331 


below  upwards,  almost  to  the  top  of  the  stem.  Brussels 
sprouts  resemble  the  kales  except  that  the  axillary  buds, 
instead  of  developing  into  side  branches,  do  not  elongate  but 
develop  into  "heads,"  which  are  in  reality  specialized  buds, 
usually  I  to  2  inches  in  diameter. 

Types. — There  are  two  general  types  of  this  plant:  tall 
Brussels  sprouts  and  dwarf  Brussels  sprouts.  The  former 
type  grows  to  a  height  of  2  to  3  feet,  is  rather  slender,  and 
the  leaves  and  "sprouts"  are  comparatively  far  apart.  It 
is  not  grown  to  any  extent  in  this  country;  dwarf  varieties 
are  preferred  here.  These  latter  seldom  exceed  2  feet  in 
height;  they  have  a  stout  stem  upon  which  the  leaves  and 
"sprouts"  are  crowded.  As  a  rule,  the  leaves  of  the  dwarf 
type  are  more  crimped  than  those  of  the  tall  type.  All  the 
types  are  cool  season  plants. 

Uses. — Brussels  sprouts  are  much  more  tender  than  com- 
mon head  cabbage.  The  smaller  "sprouts"  are  the  most 
desirable.     They  are  cooked  in  a  manner  similar  to  cabbage. 


Fig.   137. — Common  head  cabbage  (Brassica  oleraceacapitata).     Three  com- 
mon types  of  heads:  A,  pointed  or  oblong;  B,  ballhead;  C,  drumhead. 

BRASSICA  OLERACEA  VAR.  CAPITATA  (Common  Head  Cabbage) 

(Fig.  137) 
The  common  head  cabbage  produces,  the  first  year,  a  short 
stem  upon  which  are  found  numerous,  thick,  overlapping, 


332  BOTANY  OF  CROP  PLANTS 

smooth  leaves,  the  whole  forming  the  "head."  A  longitu- 
dinal section  of  a  cabbage  head  shows  the  terminal  bud,  and, 
in  some  instances,  rather  well-developed  axillary  ones. 

Types. — There  are  numerous  varieties  of  cabbages.  They 
have  been  grouped  into  a  number  of  different  types.  These 
types  vary  as  to  color,  size,  and  shape  of  head  and  leaves, 
texture  of  leaves,  length  of  stalk,  earUness,  etc.  As  grouped 
here,  the  types  may  be  distinguished  as  follows: 

Key  to  Types  of  Common  Head  Cabbage 

Leaves  smooth,  not  crimped  or  curled. 
Leaves  dark  purple  or  red,  Red  cabbages. 
Leaves  glaucous-green. 

Heads  cone-shaped,  longer  than  broad  (Fig.  137,  A),  Winningstadt  and 

Wakefield  cabbages. 
Heads  spherical  (Fig.  137,  B),  Danish  Ball  Head  cabbages. 
Heads  flat,  broader  than  long   (Fig.  137,  C),  Flat  Dutch  or  Drumhead 
cabbages. 
Leaves  crimped  or  curled,  Savoy  cabbages. 

The  red  varieties  of  cabbage  are  valued  for  pickhng  and 
slaw.  The  Wakefields  are  the  ones  most  extensively  grown 
in  trucking  districts.  There  are  two  main  types  of  Wake- 
fields:  True  Jersey  Wakefield  which  has  small  heads  pointed 
at  the  tip,  and  Charleston  Wakefield,  with  a  head  broader, 
flatter  and  more  obtuse-pointed.  Danish  Ball  Head  cab- 
bages are  most  used  for  storage  purposes.  The  Savoy  cab- 
bages, especially  when  sHghtly  frosted,  are  known  for  their 
very  excellent  flavor. 

Uses. — Cabbage  is  grown  as  a  market-garden,  truck  and 
farm  crop,  and  is  best  adapted  to  a  cool  climate.  As  a  human 
food,  it  is  most  generally  boiled  or  used  as  slaw.  Sauerkraut 
is  cabbage  cut  up  into  very  fine  pieces  and  allowed  to  ferment 
in  a  brine  made  of  its  own  juice  with  salt.  The  sour  taste  is 
due  to  the  presence  of  lactic  acid,  formed  by  the  action  of 


CRUCIFER^ 


333 


lactic-acid  species  of  bacteria  on  the  sugar  in  the  cabbage 
juice.  Ordinarily  there  is  a  maximum  of  about  i  per  cent,  of 
lactic  acid,  the  presence  of  which  prevents  putrefaction  of  the 
sauerkraut.  Among  other  organisms,  yeast  is  universally 
present  in  the  fermenting  cabbage.  Cabbages  are  also  used 
quite  extensively  for  pickling,  and  as  a  food  for  stock  and 
chickens. 


BRASSICA  OLERACEA  VAR.  CAULO-RAPA 
(Kohlrabi  or  Tijrnip-rooted  Cabbage)  (Fig,  138) 

The  stem  is  short,  much  thickened,  fleshy,  and  stands  out 
of  the  ground.  The  fleshy  part  comes  from  the  stem  above 
the  cotyledons,  hence  is  not 
root.  The  swelling  begins  at 
the  ground  line;  there  is  formed 
a  large,  spherical  body  upon 
which  are  very  prominent,  broad 
leaf  scars. 

As  to  color  there  are  two 
principal  types:  Those  with 
white  "balls"  or  stems  (White 
Vienna  Erfurt) ;  and  those  with 
purple  "balls"  (Purple  Vienna) . 

Kohlrabi  is  not  grown  exten- 
sively in  the  United  States.  It 
is  used  particularly  by  our 
foreign  population,  being  stewed 
and  eaten  like  turnips  or  ruta- 
bagas. It  is  also  a  valuable 
stock  food;  both  the  stems  and 
leaves  are  used  for  this  purpose. 
Kohlrabi  is  chiefly  grown  as  an  early  spring  crop,  less  frequently 
as  a  fall  crop.     It  does  not  endure  the  heat  of  summer. 


Fig.  138. — Kohlrabi  (Brassica 
oleracea  caulo-rapa). 


334 


BOTANY  OF  CROP  PLANTS 


BRASSICA  OLERACEA  VAR.  BOTRYTIS 
(Cauliflower,  Broccoli)  (Fig.  139) 

Cauliflower  and  broccoli  are  types  of  cabbage  in  which 
there  is  a  large  "head,"  composed  of  abortive  flowers  upon 
very  much  modified,  thickened  flower  stems  (Fig.  139).     The 


Fig.   139. — Cauliflower    (Brassica  oleracea   botrytis). 
portion  of  "head." 


A,   entire   plant;   B, 


metamorphosed  inflorescence  develops  the  first  season,  its 
numerous  short,  fleshy,  and  closely  crowded  flower  stalks 
forming  the  head,  as  indicated  above.  Subtending  the  head 
are  a  number  of  cabbage-like  leaves.     In  growing  the  vege- 


CRUCIFER^  335 

table,  these  basal  leaves  are  tied  up  about  the  fleshy,  white 
head  to  prevent  its  browning  by  the  smi. 

A  distinction  is  made  between  cauliflower  and  broccoli. 
The  latter  requires  a  longer  time  to  mature  than  cauliflower; 
furthermore,  the  heads  are  smaller  and  the  leaves  broader, 
narrower,  stiffer  and  more  numerous. 

Cauliflower  and  broccoli  are  both  cool-season  crops. 

BRASSICA  RAPA  (Turnip) 

Description. — The  common  turnip  is  a  biennial.  The 
first  year  a^swoUen  and  fleshy  tap  root  is  formed.  However, 
the  " turnip"  is  combined  primary  root  and  hypocotyl.  The 
upper  portion  to  which  the  leaves  are  attached  is  stem,  while 
the  lower  portion  to  which  secondary  roots  are  attached  is 
root. 

The  leaves  that  arise  from  the  "turnip"  the  first  season  are 
in  the  form  of  a  rosette.  They  are  oblong  to  oval,  some- 
times entire,  serrate,  or  the  later  ones  pinnate  or  pinnatifid. 
First-year  leaves  are  grass-green  and  rough-hairy.  The  sec- 
ond season,  a  stem  i  to  3  feet  tall  is  sent  up  from  the  ter- 
minal bud  in  the  center  of  the  rosette  of  leaves,  which  bears 
alternate,  clasping,  lanceolate  or  oblong,  entire  or  dentate, 
smooth  leaves.  The  flower  stem  is  branching.  The  inflores- 
cence is  a  raceme.  The  flowers  are  bright  yellow,  about  3^ 
inch  in  diameter  and  of  the  characteristic  mustard  type. 
The  fruit  is  1 3^  to  2  inches  long,  cylindrical,  and  tipped  by  a 
short  beak.  The  seeds  are  reddish  brown  in  color,  spherical, 
and  number  15  to  25  in  each  sihque. 

Geographical. — The  turnip  seems  to  have  originated  in  Europe  or  Western 
Asia.  By  cultivation,  it  has  spread  into  all  temperate  regions.  The  cul- 
tivated sorts  are  grown  as  cool-season  crops. 

Types  of  Turnips. — There  are  numerous  varieties  of  turnips, 
varying  chiefly  as  to  shape  and  color  of  "root"  (Fig.  140). 


33^ 


BOTANY   OF   CROP   PLANTS 


The  principal  varieties  grown  in  the  United  States  may 
also  be  classified  as  follows  (in  each  division  but  one  or  two 
examples  are  given) : 

Flesh  white. 

Root  entirely  white. 

Flat  (Early  White  Flat  Dutch  Strap-leaved,  Extra  Early  White  Milan). 
Spherical  (Snowball,  White  Globe  Strap-leaved). 
Oval  (White  Egg). 
Carrot-shaped  (Cow-horn). 


Fig.  140. — Types  of  turnips  (Brassica  rapa).     A,  flat;  B,  tankard  or  spindle; 
C,  globe;  D,  long.     (After  Percival.) 

Root  purple  or  red  at  top,  white  below. 

Flat  (Purple  Top  Strap-leaved,  Extra  Early  Purple-topped  MUan). 

Spherical  (Purple  Top  White  Globe). 
Root  entirely  red  (Scarlet  Kashmyr). 
Flesh  yellow. 
Root  entirely  yeUow  (Golden  Ball). 
Root  green  at  top,  yellow  below  (Amber  Globe), 
Root  red  at  top,  yellow  below  (Early  Red  Top  Globe). 

Structure  and  Uses. — It  will  be  recalled  that  the  greater 
portion  of  a  turnip  is  tap  root.  In  cross-section,  it  shows  the 
following  layers  (Fig.  141) : 

1.  Outer  layer  or  cortex  (bark). 

2.  Cambium. 

3.  Main  flesh  of  turnip  (wood  and  pith).  J 


CRUCIFER^ 


337 


In  the  fleshy  root  of  the  turnip,  the  walls  of  the  cells  which 
make  up  the  wood  are  not  lignified,  and  hence  the  tissue  is 
soft,  unUke  ordinary  wood  tissue.  The  medullary  rays  are 
very  indistinct.  Some  turnips  are  coarse  in  texture  and 
such  are  used  for  stock  food.     The  turnips  of  finer  texture 


'--cortex 


"Z^  -rr  .^\-  camhwsm 


Fig.   141. — Root  of  turnip  (Brassica  rapa)  in  cross-section.     Diagrammatic. 

are  used  as  food  by  man.     In  the  South  the  variety  Seven 
Top  is  grown  as  a  green  forage  and  green  manure. 


BRASSICA  CAMPESTRIS  (Rutabaga  or  Swede  Turnip)  (Fig.  142) 

Description. — This  species  resembles  very  closely  B.  rapa, 
the  common  turnip.  Rutabagas  or  "Swedes,"  have  a  short 
stem  or  "neck"  at  the  upper  part  of  the  vegetable.  It  is 
this  character  which  easily  distinguishes  the  rutabaga  vege- 
table from  that  of  turnip.  The  flesh  is  solid  and  yellow  or 
orange  in  color.  The  first  leaves  are  bluish  white,  and  all 
leaves  have  thick,  fleshy  petioles.  The  yellow  flowers  are 
larger  than  those  of  the  turnip,  and  the  claws  are  longer. 

Uses. — Rutabagas  or  "Swedes"  have  less  water  than  com- 
mon turnips.  They  are  commonly  grown  as  a  food  for 
stock,  but  are  also  eaten  in  large  quantities  by  man.     They 


338  BOTANY  OP  CROP  PLANTS 

develop  the  sweetness  and  flavors  for  which  they  are  so  well 
known  only  in  the  Northern  States  where  the  nights  are  cool. 

BRASSICA  NAPUS  (Rape) 

Description. — Rape  is  a  biennial  plant,  growing  to  a 
height  of  2  to  3  feet.  It  thrives  best  in  those  regions  with 
cool  summers.     The  stem  is  branched   to  a  considerable 


Fig.  142. — Rutabaga  (Brassica  campestris). 

extent.  There  is  no  swollen  root.  The  lower  leaves  are 
lyrate,  the  upper  ones  oval  to  lanceolate  and  clasping  the 
stem.  The  inflorescence  is  of  the  typical  racemose  type. 
The  flowers  are  bright  yellow.  The  seeds  are  black  or  dark 
purple.  The  seedlings  and  young  plants  resemble  those  of 
B.  campestris  (rutabaga). 

Varieties  and  Uses. — The  principal  variety  of  rape  in  the 
United  States  is  Dwarf  Essex  or  English  rape.     This  is  a 


CRUCIFER^  339 

variety  used  for  its  green  foliage,  and  hence  is  treated  as  an 
annual.  This  type  of  rape  is  used  as  a  fall  pasture  for  sheep,- 
pigs  or  cows,  as  a  green  manure,  and  as  a  soiUng  crop,  catch 
crop,  or  cleaning  crop.  "Rape  cake,"  made  from  the  seeds 
by  expressing  the  oil,  is  used  as  a  stock  food,  and  the  oil 
itself  is  of  some  value.  About  42  per  cent,  of  the  seed  is 
composed  of  rape  oil. 

BRASSICA  NIGRA  (Black  or  Brown  Mustard) 

Description. — The  black  mustard  is  an  annual  herb  2  to 
7  feet  tall,  and  freely  branching.  The  lower  leaves  are  hairy 
and  deeply  pinnatifid,  with  one  large,  terminal  lobe  and 
two  to  four  smaller,  lateral  ones;  the  lobes  are  coarsely 
toothed.  The  upper  leaves  have  much  shorter  petioles  than 
the  lower,  or  they  are  entirely  sessile,  and  the  blades  are 
entire  and  oblong  or  lanceolate.  The  flowers  are  bright  yel- 
low. The  pods  are  slender,  four-sided,  oppressed  against  the 
stem,  and  measure  about  }4  inch  or  more  in  length.  The 
seeds  are  dark  brown. 

Black  mustard  is  a  native  of  Europe  and  Asia.  It  has 
become  naturahzed  in  this  country  and  has  escaped  from 
cultivation,  becoming  frequently  a  troublesome  weed. 
.  Black  mustard  resembles  charlock  {Brassica  arvensis), 
one  of  the  worst  pests  in  grain  fields  of  the  Middle  West. 
Charlock  has  long,  knotted  pods  with  stout  beaks,  while  the 
pods  of  black  mustard  are  short,  four-angled,  and  with  short 
beaks.  The  pods  of  white  mustard  are  somewhat  bristly. 
Charlock,  black  mustard  and  white  mustard  are  propagated 
by  seeds.  In  their  eradication,  no  attention  needs  to  be 
directed  toward  the  starving  out  of  rootstocks,  which  are  so 
typical  of  perennial  weeds.  Every  effort  is  made  to  prevent 
them  from  going  to  seed.  Much  success  has  attended  the 
use  of  chemical  herbicides,  chiefly  iron  sulfate,  in  eradicating 


340  BOTANY  OF  CROP  PLANTS 

the  mustards  from  grain  fields.  All  grasses  are  resistant  to 
injury  from  this  spray,  but  the  young  mustards,  and  niany 
other  weeds,  are  quite  easily  killed  by  it.  This  is  due  to  the 
fact  that  the  spray  does  not  adhere  so  readily  to  the  smooth 
grass  leaves  as  to  the  mustard  leaves;  moreover,  although  the 
tips  of  grass  leaves  are  injured,  the  growing  tissue  at  the  leaf 
base  may  not  be  touched  by  the  spray,  and  hence  the  recovery 
is  rapid: 

Related  Species. — It  is  closely  related  to  the  white  mustard  which  is  de- 
scribed hereinafter,  and  to  Chinese  or  Indian  mustard  (Brassicajuncea).  The 
latter  is  adventive  from  Asia  in  this  country,  often  a  bad  weed,  and  sometimes 
its  leaves  are  used  for  "greens."  In  the  Indian  mustard,  the  pods  are  i  to  2 
inches  long,  and  some  of  the  forms  have  leaves  twice  the  size  of  those  in  the 
ordinary  black  or  white  mustards.  The  Japanese  or  pot-herb  mustard 
(Brassica  japonica)  is  introduced  into  the  United  States.  It  has  thin,  soft 
leaves  which  are  valued  as  "greens." 

Uses. — The  plant  is  used  mainly  for  garnishing,  also  in 
salads  and  in  the  preparation  of  meat  dressings  and  sauces. 
Occasionally  it  is  boiled  like  spinach.  Table  mustard  is  the 
ground  seeds  of  black  mustard.  The  aroma  and  pungency 
of  mixed  mustard  (table  mustard)  does  not  exist  in  the  seed 
itself,  but  is  given  rise  to  when  the  ground  seed  is  mixed  with 
water.  This  pungent,  volatile  oil  is  an  allylthiocyanate  and 
is  formed  by  the  action  of  a  specific  enzyme,  myrosin,  upon 
potassium  myronate — a  glucoside  present  in  the  seed. 

BRASSICA  ALBA  (White  Mustard) 

This  species  has  characteristics  very  similar  to  those  of 
black  mustard.  It  is  distinguished  from  the  latter  chiefly  by 
its  Hghter  colored  bristly  pods,  and  its  Hghter  colored  and 
larger  seeds. 

The  plant  is  a  native  of  Europe,  Asia  and  northern  Africa. 
It  is  used  similarly  to  the  black  mustard,  and  in  addition  is 


CRUCIFER^  341 

sometimes  used  as  a  green  manure.     The  mixed  mustard 
from  this  species  is  less  pungent  than  that  from  B.  nigra. 

RAPHANUS  SATIVUS  (Garden  Radish) 

Habit. — The  common  garden  radish  is  an  annual  or  bien- 
nial herb.  It  may  produce  fruit  the  same  year,  when  planted 
early  in  the  season,  while,  if  planted  late,  it  produces  a 
fleshy  tap  root  the  first  year,  which  may  be  kept  over  the 
winter  until  the  next  year,  when  it  produces  fruit. 

Root. — The  radish  vegetable  is  mainly  a  tap  root,  varying 
in  size,  shape,  and  color.  At  the  top  is  a  short  hypocotyl 
(stem).  The  laterals  from  the  tap  root  are  few  in  number 
and  very  slender. 

Stem. — From  the  hypocotyl  or  crown  of  the  radish,  there 
first  appears  a  rosette  of  leaves,'  and  later  an  erect,  freely 
branching  stem,  i  to  23^  feet  tall.  This  stem  may  be  sparsely 
pubescent  with  stiff  hairs,  especially  below,  or  rarely  gla- 
brous throughout. 

Leaves. — The  basal  and  lower  leaves  are  deeply  lyrate-pin- 
natifid,  4  to  8  inches  long;  the  upper  leaves  are  few,  small, 
and  oblong. 

Inflorescence  and  Flowers. — The  inflorescence  is  an  elon- 
gated raceme  (Fig.  132).  Th.e  flowers  are  of  the  typical  mus- 
tard type;  the  sepals  are  erect  and  sac-like  at  the  base;  the 
petals  rose-hlac  or  white. 

Fruit. — The  pods  are  i  to  i3^  inches  long,  two-  to  three- 
seeded,  fleshy,  or  corky  with  a  spongy  tissue  separating  the 
seeds;  the  pods  are  not  longitudinally  grooved  or  promi- 
nently constricted;  they  are  capped  by  a  long  conic  beak 
which  may  equal  or  exceed  the  pod  itself. 

Seeds  and  Seedling. — Th^  seeds  are  small  and  of  a  yellowish 
color;  on  one  side,  when  viewed  with  a  hand  lens,  may  be 
seen  a  small  spot,  in  reahty  double,  made  up  of  the  hilum  and 


342  BOTANY  OF  CROP  PLANTS 

micropyle.  Endosperm  is  absent.  The  cotyledon  leaves 
are  persistent  until  the  root  becomes  of  considerable  size  and 
may  be  seen  at  the  crown  of  the  radish,  lying  flat  against 
the  root.  Each  cotyledon  leaf  is  oblong  in  outhne  and 
broadly  notched  at  the  tip. 

Geographical  Distribution  and  Origin. — The  common 
radish  is  found  growing  wild  in  the  temperate  regions  of  the 
Old  World.  It  was  introduced  into  this  country  by  the 
earlier  settlers  and  here,  as  wherever  it  is  planted,  has 
escaped  from  gardens,  becoming  in  many  instances  a  rather 
common  wayside  plant.  Radishes  that  run  wild  in  this 
manner  produce  a  root  that  is  slender  and  woody,  possibly 
reverting  to  the  type  from  which  it  came.  E.  A.  Carriere 
held  the  opinion  that  our  common  garden  radish  has  sprung 
from  Raphanus  raphanisirum,  the  wild  radish  or  white 
charlock,  and  a  common  weed  throughout  Europe,  and  also 
adventive  in  the  United  States.  He  bases  his  opinion  on  his 
own  experiments  which  in  brief  were  as  follows :  The  seeds  of 
Raphanus  raphanistrum,  which  has  very  woody  and  slender 
roots,  were  planted  and  after  five  years  of  care  there  was 
developed  a  type  of  root  which  was  fleshy,  large,  and  varying 
in  form  and  color.  The  roots  developed  had  the  flavor  of  our 
garden  radishes  and  were  edible.  In  spite  of  the  experiments 
of  Carriere,  many  botanists  believe  that  white  charlock  is  not 
the  projenitor  of  the  radish.  For  example,  it  is  known  that 
the  garden  radish  long  ago  was  a  common  plant  in  India, 
China,  and  Japan.  But  Raphanus  raphanistrum  is  not 
found  in  these  countries,  and  furthermore,  the  main  move- 
ment of  cultivated  plants  has  not  been  from  Europe  to  Asia, 
but  from  the  orient  to  the  Occident.  The  true  history  of  the 
radish  seems  to  be  unknown. 

Closely  Related  Species. — Raphanus  raphanistrum,  white  charlock,  men- 
tioned above,  may  be  quite  easily  mistaken  for  the  common  radish,  especially 


CRUCIPER^  "  343 

when  the  latter  has  run  wild.  White  charlock,  however,  has  yellowish 
flowers  turning  white  or  purplish,  and  a  silique  which  is  much  more  conspicu- 
ously jointed  and  longitudinally  grooved  than  that  of  common  radish. 

Raphanus  sativus  caiidatus,  the  rat-tailed  radish,  an  annual  herb  native  to 
South  Asia,  has  a  slender,  twisted  pod,  8  to  lo  inches  long,  which  thus  differs 
from  the  short,  thick  ones  of  common  radish.  These  pods  form  the  edible 
portion  of  the  plant. 

Types  of  Radishes. — As  to  seasonal  development,  there  are 
three  groups  of  radishes,  as  follows: 

1 .  Early  or  Forcing  Radishes. — A  forcing  crop  is  one  grown 
out  of  season,  and  out  of  its  natural  environment.  Hot 
beds,  cold  frames  and  greenhouses  are  the  forcing  structures 
in  use.  The  chief  crops  forced  besides  radishes  are  lettuce, 
tomatoes,  cucumbers,  cauHflowers  and  beans.  Early  or 
forcing  radishes  reach  an  edible  size  very  soon,  often  in  from 
twenty  to  thirty  days.  In  this  group,  belong  such  varieties 
as  French  Breakfast,  Early  Scarlet  Turnip,  Scarlet  Globe, 
Long  Scarlet  Short  Top,  and  White  "Icicle." 

2.  Summer  Radishes. — The  roots  of  this  group  are  slower  in 
maturing,  requiring  from  six  to  eight  weeks  to  reach  a 
marketable  size,  and  are  larger  than  those  of  the  first  group. 
Here  belong  such  varieties  as  Long  White  Vienna,  Chartiers, 
White  Strasburg,  Stuttgart. 

3.  Winter  Radishes. — These  have  a  compact  and  j&rm  flesh 
and  keep  well  through  the  winter.  The  roots  require  several 
months  to  reach  maturity,  often  attaining  a  large  size. 
Common  winter  varieties  are  Black  Spanish,  Sakurajima  or 
Japanese  radish,  and  White  Chinese. 

As  to  shape,  radishes  may  be  classified  as  follows  (Fig.  143): 

1.  Round  or  turnip-shaped  (Early  Scarlet  Turnip,  Scarlet  Globe,  Scarlet 
Gem). 

2.  Olive  or  oval-shaped  (intermediates)  (French  Breakfast,  Early  Scarlet 
Olive-shaped,  Black  Spanish). 

3.  Half -long  (Scarlet  Half-long,  French,  Half -long  Deep  Scarlet),  . 

4.  Long  (Vienna,  Chartier,  Long  Scarlet,  White  "Icicle"). 


344 


BOTANY   OF   CROP  PLANTS 


Radishes  vary  in  color:  some  varieties  are  white,  others  pink,  red,  purple, 
mottled,  or  black,  or  red,  tipped  with  white,  etc. 

RADICULA  (Water  Cress  and  Horse-radish) 

Members  of  this  genus  are  branching  herbs  with  simple  or 
pinnate  lobed,  dissected,  or  rarely,  entire  leaves.    Flowers  are 


Fig. 


143. — Types  of  radishes   (Raphanus  sativus).     A,  turnip-shaped;   B, 
globular;  C,  olive-shaped;  D,  half-long;  E,  long.     (.After  Corbetl.) 


in  elongated  racemes;  they  have  spreading  sepals,  yellow  or 
white  petals,  and  one  to  six  stamens.  The  siliques  are  short  or 
elongated,  pencil-shaped,  without  a  stalk  or  stipe,  with  one- 
nerved  valves ;  there  are  numerous  turgid  seeds  in  two  rows  in 
each  cell,  or  very  rarely  one  row  in  each  cell. 


CRUCIFER^  345 

The  genus  is  one  of  wide  distribution;  it  is  most  abundant 
in  the  north  temperate  zone. 

There  is  a  rather  large  number  of  species,  some  of  which  are 
amphibious,  others  aquatic.  The  two  principal  economic 
species  are  Radicula  armoracia  (horse-radish)  and  Radicula 
nasturtium-aquaticum  (water  cress) .  The  former  is  terrestrial, 
the  latter  aquatic. 

RADICULA  ARMORACIA 

(Horse-radish)  (Fig.  144)] 

Description. — Horse-radish  is  a  hardy  perennial  from  a 
white,  fleshy,  cylindrical  root  which  branches  at  the  lower, 
end.  The  fibrous  roots  may  penetrate  to  a  depth  of  6  or  7 
feet.  In  propagating  the  plant,  the  slender  side  roots  usually 
are  used;  pieces  of  the  main  root  are  also  used  for  this  purpose. 
The  plants  are  2  to  3  feet  tall,  branching,  with  long-petioled, 
oblong,  basal  leaves,  6  to  12  inches  long,  that  have  crenate, 
sinuate  or  pinnatifid  margins.  The  upper  leaves  are  smaller, 
sessile,  oblong,  or  lanceolate.  The  racemes  are  terminal  or 
axillary,  and  bear  white  flowers.  The  pods  are  oblong  or 
nearly  globose  and  bear  a  short  persistent  style.  In  cultiva- 
tion, the  plant  seldom  produces  seed,  but  is  propagated  by 
root  cuttings. 

Geographical. — Horse-radish  is  a  native  of  Europe.  It  is  a  common  liome 
garden  plant  in  the  United  States,  and  in  some  instances  has  escaped  from 
cultivation  and  become  a  troublesome  weed. 

Uses. — The  root  is  grated  or  scraped,  sometimes  mixed 
with  vinegar,  and  used  as  a  condiment. 

RADICULA  NASTURTIUM-AQUATICUM 
(Water  Cress) 

Description. — This  is  a  perennial,  aquatic  plant  with  long 
floating  or  creeping  stems  which  readily  take  root  at  the 


346 


BOTANY   OF   CROP   PLANTS 


nodes.     The  leaves  are  compound  and  odd-pinnate   (Fig. 
145);  the  terminal  segment  is  larger  than  the  laterals,  all  of 


Fig. 


-Horse-radish  (Radicula  armoracia).     A,  basal  leaf;  B,  fruit;  C, 
cauline  leaves  and  inflorescence. 


which  are  slightly  wavy  on  the  margin  and  of  a  dark  green 
color.  The  white  flowers  are  in  terminal  racemes;  the  petals 
are  twice  as  long  as  the  sepals.     The  sihques  (Fig.  145)  are 


CRUCIFER^ 


347 


slightly  curved,  on  pedicels 
of  equal  length,  and  bear 
a  few  seeds  in  two  rows. 

Geographical. — Water  cress  is 
a  native  of  Europe  and  Northern 
Asia,  but  has  become  naturalized 
in  both  North  and  South  Amer- 
ica. It  is  widespread  in  North 
Ar^ierica. 


References 

Carriere,  E.  a.:  Une  nouvelle 

plante  fourragere  at  econom- 

ique.     Journ.  d'Agric.   Prat. 

Annee,  ^^t  tome  ii:  845-847, 

1869. 
GoFF,  E.  S.:  Vegetables:  Turnip- 

6th  Ann.  Rept.  N.  Y.  Agr. 

Exp.  Sta.,  168-190,  1887. 
Henslow,    G.:    The  History  of 

the    Cabbage   Tribe.     Jour. 

Roy.   Hort.    Soc.    (London), 

34: 15-23,  1908-1909. 
Shaw,  T.:  The  Rape  Plant:  Its 

History,  Culture,  and  Uses. 

U.  S.    Dept.   Agr.  Farmers' 

Bull.  11:  1-20,  1893. 


Fig. 


145. — Water  cress  (Radicula  nas- 
turtium-aquaticum) . 


CHAPTER  XXVI 

ROSACEA  (Rose  Family) 

The  Rosacese  are  well  represented  m  North  Temperate 
climates.  There  are"  about  1,200  species  within  65  genera. 
The  most  important  genera  from  the  crop  standpoint  are 
Rubus  (raspberry,  blackberry  and  dewberry),  and  Fragaria 
(strawberry) .  Other  genera  of  importance  or  of  interest  are 
Spircea,  an  ornamental  shrub,  Potentilla  (five-finger  or  cinque- 
foil),  Cercocarpus  (mountain  mahogany),  and  Rosa  (rose). 

Leaves. — The  leaves  are  alternate,  either  simple  (as  in 
some  Rubus  species),  or  compound  (strawberry,  rose). 
There  are  two  rather  prominent  stipules,  free  from  or  adher- 
ent to  the  petiole. 

Inflorescence.— There  are  several  different  kinds  of  flower 

clusters  in  the  family.     It  is  a  terminal  corymb  (flat-topped 

raceme)     in     Opulaster,     either     racemose, 

cymose,  corymbose  or  paniculate  in  SpircBu, 

terminal  or  axillary  and  soHtary,  racemose 

or  paniculate  in  Rubus,  and  corjnnbose  or 

racemose  in  the  strawberry.     It  is  interest- 

FiG.  i46^Fiorai  ing   to  notc  the  great  number  of  different 

diagram  of  Rubus.   gorts  of  iuflorescences  in  this  one  family,  and 

{After  Wossidlo.)  .         .  ,      ,  ,  ^        .,       .         ,  .   , 

contrast  it  with  the  mustard  family,  m  which 
the  raceme  is  the  one  prevailing  type,  or  with  the  carrot 
family  in  which  the  umbel  is,  with  the  exception  of  one 
genus,  the  only  type,  or  with  the  sunflower  family,  all  mem- 
bers of  which  have  a  head  inflorescence. 

Flowers. — The  flowers  (Fig.  146)  are  regular,  and  usually 
perfect.     In  some  cultivated  strawberries  imperfect  flowers 
348 


ROSACEA 


349 


are  borne.  The  calyx  is  free  from  or  grown  to  the  ovary, 
five-lobed,  and  sometimes  subtended  by  a  set  of  bracts 
(epicalyx,  as  in  strawberry).  The  petals  are  distinct,  as 
many  as  the  lobes  of  the  calyx  and  inserted  on  the  margin  of 


rece'pkcle 
drupeki 

ca^K  lobe 


■6li^ma 


Fig.  147. — American  red  raspberry  (Rubus  strigosus).     A,  median  lengthwise 
section  of  flower,  X  4;  B,  same  of  fruit,  X  4;  C,  single  immature  pistil,  X  5- 


the  disk  (Fig.  147).  This  disk  is  an  outgrowth  of  the  recep- 
tacle and  forms  a  flat  rim  about  the  calyx  base.  In  cultivated 
roses  there  are  numerous  petals  which  have  developed  from 
primordia  that  normally  become  stamens.     This  bears  out  the 


350  BOTANY  OF  CROP  PLANTS 

belief  that  stamens  are  leaves,  morphologically.  The  pro- 
duction of  supernumerary  petals  is  known  as  "doubling." 
The  stamens  are  numerous,  distinct,  and  attached  to  the 
margin  of  the  toral  disk  (Fig.  147).  The  anthers  are  small 
and  two-celled.  The  carpels  are  usually  numerous  and  dis- 
tinct, or  rarely  attached  to  the  calyx.  The  ovary  is  one-celled 
(rarely  imperfectly  two-celled)  with  a  terminal  or  lateral  style, 
and  with  from  one  to  many  ovules. 

Fruit. — The  fruit  is  a  follicle  in  Spircsa,  an  aggregate  of 
drupelets  in  raspberry,  blackberry  and  dewberry,  or  an 
aggregate  of  achenes  in  strawberry  and  rose.  The  folHcle 
is  a  pod-like  fruit,  with  one  carpel,  which  opens  along  one 
side  only  and  usually  bears  numerous  seeds.  The  true  pod, 
characteristic  of  the  pea  family,  is  a  one-carpelled  fruit, 
which  splits  along  two  sides.  It  will  be  remembered  that 
the  capsule  has  several  carpels.  A  drupelet  is  a  small 
drupe —  a  one-seeded  fruit  with  a  fleshy  mesocarp  and  stony 
endocarp. 

Key  to  Important  Genera  of  Rosace^e 

Fruit  not  inclosed  in  a  hollow  receptacle,  i.e.,  the  calyx  not  constricted  over 
the  fruit. 
Carpels  becoming  follicles,  Spiraa. 
Carpels  become  small  drupelets  crowded  on  a  fleshy  receptacle,'  Rubus 

(raspberry,  blackberry,  dewberry). 
Carpels  becoming  dry  achenes. 
Style  becoming  long  and  plumose,  Cercocarpus  (mountain  mahogany). 
Style  short. 

Receptacle  fleshy  in  fruit,  Fragaria  (strawberry). 
Receptacle  not  fleshy  in  fruit,  Potenlilla  (five-finger  or  cinque-foil). 
Fruit  inclosed  in  a  hollow  receptacle,  i.e.,  the  calyx  constricted  over  the 
fruit,  Rosa  (rose). 

RUBUS  (Raspberry,  Blackberry,  Dewberry) 

Stems. — The  plants  of  this  genus  are  usually  shrubs, 
rarely  herbs  {Rubus  Chamcemorus ,  cloudberry,  knotberry  or 


ROSACE/E 


351 


mountain  bramble).  They  are  usually  designated  as 
"brambles."  The  stems  are,  as  a  rule,  prickly,  erect,  decum- 
bent, or  creeping.  The  stems  ("canes")  commonly  die  after 
one  or  two  years,  new  ones  being  sent  up  from  the  roots.  The 
main  growth  of  the  stem  is  made  during  the  first  year,  in 


Fig.    148. — Fruiting   branch   of  American  red  raspberry   (Rubus  strigosus). 

most  Rubi;  side  branches  are  produced  the  second  year;  the 
flowers  and  fruit  are  developed  on  these  side  branches.  The 
entire  cane  usually  becomes  weak  and  dies  after  fruiting. 
This  suggests  the  advisabiUty  of  removing  canes  once  they 
have  borne  fruit. 

Propagation.^Red    rasi)berrics,    blackberries    and    dew- 
berries (rarely)  "sucker"  readily.     This  natural  tendency  to 


352  BOTANY  or  CROP  PLANTS 

send  up  sprouts  from  the  roots  is  taken  advantage  of  by  the 
fruit-raiser.  All  plants  which  reproduce  naturally  from 
suckers  arc  easily  propagated  from  root  cuttings.  Black- 
cap raspberries  and  dewberries  produce  stolons.  A  shoot 
bends  over  by  its  own  weight  and  takes  root  at  the  tip. 
When  once  the  tip  has  rooted  well,  the  shoot  may  be  cut  loose 
from  the  parent  stem  and  such  rooted  tips  used  as  "sets." 

Leaves. — These  are  alternate,  simple,  palmately  lobed  or 
compound  three-  to  seven-foHate,  and  bear  persistent 
stipules.  In  Rubus  trhialis,  southern  dewberry,  the  leaves 
arc  evergreen. 

Inflorescence. — The  flowers  are  terminal  or  axillar\-,  soli- 
tary, in  panicles  or  racemes.  The  flowers  and  fruit  in  all 
representatives  of  the  genus  Rubus  are  borne  on  shoots  which 
arise  from  the  growth  of  the  year  before.  For  example,  in 
19 13,  a  shoot  (cane)  is  sent  up  from  the  root.  This  bears 
leaf  buds  entirely.  In  1914,  these  lateral  buds  elongate,  and 
some  of  the  resulting  shoots  bear  inflorescences.  The 
shoots,  developed  in  1913,  once  having  borne  fruit  in  1914,  are 
no  longer  useful.  The  cutting  out  of  these  useless  shoots  will 
induce  the  development  of  new  ones  from  the  roots. 

Flowers. — The  flowers  (Fig.  147,  A)  are  rather  large,  regu- 
lar, and  usually  perfect.  In  Rubus  vilifolius,  the  Pacific  Coast 
dewberry,  however,  there  are  both  hermaphroditic  and  pistil- 
late plants.  Rubus  Chamccmorus  is  flioccious.  The  recep- 
tacle is  Hat  or  convex.  The  live-parted  calyx  is  persistent 
in  the  fruit.  There  are  five  petals,  which  are  usually  white, 
and  deciduous.  The  stamens  are  numerous,  and  attached 
at  the  base  of  the  disk.  The  numerous  pistils  are  separate 
and  crowded  on  the  rece[)tacle;  each  pistil  bears  a  single 
thread-like  style.  The  styles  arc  hairy  and  somewhat 
broadened  at  the  base  in  the  raspberry;  while  they  are 
narrow  and  free  from  hair  at  the  base  in  the  blackberry. 


ROSACEA  353 

Pollination. — As  a  rule,  the  anthers  and  stigmas  mature 
simultaneously.  There  is  abundant  nectar  secreted  by  a 
fleshy  ring  on  the  margin  of  the  receptacle,  inside  of  the 
stamens.  Insects  facilitate  polhnation.  Better  yields  are 
secured,  in  the  case  of  some  dewberries,  if  they  are  planted 
adjacent  to  another  variety  so  that  cross-fertiHzation  will 
result. 

Fruit. — The  fruit  (Fig.  147)  of  the  genus  is  an  aggregate. 
The  numerous  pistils  ripen  into  drupelets  which  cling  to- 
gether to  a  greater  or  less  degree.  In  the  dewberries  and 
blackberries,  the  drupelets  are  firmly  attached  to  the  recep- 
tacle while  in  raspberries  the  drupelets  readily  separate  from 
the  receptacle  when  the  fruit  is  being  picked,  clinging  together 
in  the  form  of  a  cup.  The  exposed  surface  and  the  angles 
between  the  faces  of  each  drupelet  are  pubescent  in  the  rasp- 
berry, and  the  faces  themselves  are  glabrous.  The  sticking 
together  of  the  drupelets  is  due  to  the  interlocking  of  these 
crooked  hairs.  The  blackberry  and  dewberry  drupelets  are 
glabrous  throughout. 

Geographical. — The  Rubi  are  of  wide  geographic  distribution;  the  greater 
number  of  species,  however,  occurs  in  North  Temperate  regions. 

Classification. — The  numerous  members  of  the  genus  fall 
into  three  groups  which  may  be  distinguished  as  follows : 

Key  to  Groups  of  Genus  Rubus 

Drupelets  firmly  attached  to  receptacle,  not  separating  from  the  latter  when 
fruit  is  being  picked. 
Stems  upright;  plant  propagating  by  suckers;  lower,  outer  flowers  open 

first,  Blackberries. 
Stems  trailing;  plant  propagating  by  tips;  center  flowers  open  first,  Dew- 
berries. 
Drupelets  readily  separating  from  the  receptacle  when  fruit  is  being  picked, 
clinging  together  in  form  of  cup,  Raspberries. 
23 


354  BOTANY  OF  CROP  PLANTS 

BLACKBERRIES  '' 

Only  those  species  are  considered  in  the  following  keys 
which  have  yielded  us  our  important  fruit-bearing  varieties. 
The  key  considers  the  groups  of  blackberries  as  given  by 
L.  H.  Bailey  in  "The  Evolution  of  Our  Native  Fruits." 

Key  to  Species  of  Blackberries 

Inflorescences  conspicuously  loose,  the  few  flowers  scattered  on  long  pedi- 
cels, Rubus  nigrobaccus  X  R.  villosus  (loose-clustec  blackberries  or  black- 
berry-dewberry). 
Inflorescences  more  compact,  the  flowers  not  so  scattered  along  the  main 
axis. 
Inflorescences  leafy,    i.e.,  pedicels  subtended    by  leaves,  Rubus    argutus 

(leafy-cluster  blackberries). 
Inflorescences  entirely  or  almost  leafless. 
Clusters  long. 
Berries  black,   R.  nigrobaccus    (common    long-cluster    or  high-bush 

blackberry). 
Berries  cream-colored  or  pink,    R.  nigrobaccus  var.  albinus   (white 
blackberry). 
Clusters  short. 
Lower  surfaces  of  leaves  white-pubescent;  plants  i  to  3  feet  tall,  very 

thorny,  R.  cuneifoUus  (sand  blackberry). 
Lower  surfaces  of  leaves  pubescent  but  not  whitish;  plants  i  to  8  feet 
tall,  thorny,  R.  nigrobaccus  v&r.sativus  (short-cluster  blackberries). 

Rubus  nigrobaccus. — The  tall  stems  are  furnished  with  strong,  hooked 
prickles.  The  long-stalked  leaves  have  ovate  and  distinctly  pointed  leaflets. 
Inflorescences  are  long,  glandular-hairy  racemes  with  large,  showy  flowers  on 
pedicels  that  stand  out  almost  at  right  angles.  The  fruit  is  firm,  oblong, 
sweet,  and  aromatic. 

The  plant  is  found  throughout  eastern  United  States  and  northward  into 
Canada.  The  variety  Taylor  is  the  best  known.  Snyder  and  Kittatinny 
are  common  varieties  of  the  short-cluster  blackberries.  The  white  blackberry 
has  greenish-yellow  stems  and  cream-white  fruits,  and  occasionally  grows 
wild. 

Rubus  nigrobaccus  X  R.  villosus. — The  loose-cluster  blackberries  are  con- 
sidered to  be  hybrids  between  the  high-bush  or  long-cluster  blackberry  and 
the  northern  dewberry.  The  plants  are  rather  low  and  spreading  and  have 
characteristic,  broad,  jagged  leaflets. 


ROSACE.E 


355 


The  fruits  arc  small  and  globular  or  globular-oblong,  and  grow  in  smal' 
clusters.     Wilson  and  Rathbun  are  typical  varieties. 

Rubus  aigutus. — The  plants  are  erect,  stiff,  prickly,  and  with  stems 
stronglj'  angled,  almost  grooved.  The  small  leaflets  are  firm  and  rather  rigid, 
and  coarsely  toothed.  Inflorescences  are  short  and  leafy.  The  fruit  is  small, 
globular,  and  black.  The  species  is  found  growing  wild  from  New  England 
to  I'lorida  and  Arkansas.  Common  varieties  are  Dorchester,  Early  Harvest, 
and  Brunton  Early. 

Rubus  cuneifolius. — The  sand  blackberry  is  a  stifT,  thorny  plant  about 
3  feet  tall.  The  leaflets  are  thick,  obovate,  and  white-pubescent  beneath. 
Inflorescences  are  short  and  bear  but  a  few  (two  to  eight)  flowers.  The  fruit 
is  of  medium  size,  sweet,  and  desirable.  This  species  grows  wild  from  south- 
ern New  York  and  Pennsylvania  to  Florida,  Louisiana  and  Missouri.  Topsy 
is  the  common  cultivated  variety;  it  often  does  not  have  the  pubescence  of 
the  species. 


Fu"..    149. — Xurlhcrn  dewberry  (Rubus  villosus). 
DEWBERRIES 

These  differ  from  blackberries  in  their  trailing  habit, 
cymose  inflorescences,  and  propagation  by  tips.  They 
ha\-e  received   tin-  iianic  "trailinLr  black.I)err\'."     There  are 


356  BOTANY  OF  CROP  PLANTS 

four  principal  groups  of  dewberries,  which  are  distinguished 
in  the  following  key: 

K.EY  TO  Principal  Species  of  Dewberries 

Leaves'evcrgrecn,  R.  Irivialis  (southern  dewberry). 
Leaves  deciduous. 

Buds  tipped  by  the  united  ends  of  the  sepals,  forming  a  spine;  flower  clus- 
ters forking  into  two  or  three  parts,  R.  invisus  (northern  dewberry). 
Buds  not  tipped  by  the  united  ends  of  the  sepals  to  form  a  spine. 

Both  hermaphrodite  and  pistillate  plants;  leaflets  coarsely  toothed,  R. 

vilifolius  (western  dewberry). 
Plants  all  perfect;  leaflets  fmely  toothed,  R.  villostis  (northern  dewberry). 

Rubus  trivialis.— These  are  trailing  shrubs,  with  stout,  hooked  prickles  and 
bristles  on  the  stems,  and  with  upright  branches  3  to  9  inches  tall.  The  leaves 
are  trifoliate,  pctioled,  and  with  oval,  leathery,  serrate,  evergreen  leaflets. 
The  inflorescences  are  one-  to  five-flowered.  The  flowers  are  large,  white, 
and  have  petals  that  are  much  longer  than  the  sepals.  The  fruit  is  black, 
and  up  to  i  inch  long.  The  species  occurs  from  Virginia  to  Florida  and  west- 
ward to  Texas  and  Missouri.  The  best-known  horticultural  variety  is 
.Manatee. 

Rubus  invisus. — The  stems  are  moderately  prickly.  'J"he  leaflets  are  large 
and  coarsely  and  simply  dentate.  The  erect  peduncles  are  elongated.  The 
large  flowers  are  on  long  pedicels;  flower  buds  are  tipped  by  the  united  ends 
of  the  sepals.  The  species  is  reported  by  Bailey  as  growing  wild  from  New 
York  to  Alabama  and  east  to  Kansas  and  Missouri.  The  chief  varieties  are 
Hartel  and  Afammoth. 

Rubus  vitifolius. — This  species  occurs  in  California,  Oregon,  Washington 
and  Idaho.     Skagit  Chief  is  the  principal  form  in  cultivation. 

Rubus  villosus. — The  plants  are  robust,  with  smooth  stems  and  large, 
thick  leaves,  which  have  three  to  seven  oval  or  ovate,  long-pointed  and  sharply 
double-toothed  leaflets.  The  inflorescences  are  one  to  three-flowered,  leafy, 
and  cymose.  The  fruit  is  globular,  and  has  a  few,  shining-black,  and  sweet 
drupelets.  This  is  the  common  dewberry  of  the  Xorlhern  States;  it  is  found 
growing  wild  from  Newfoundland  to  Virgina  and  westward  to  Minnesota  and 
Kansas.  Windom,  Geer  and  Lucretia's  Sister  are  varieties.  The  Lucretia 
dewberry  {variety  roribaccus)  is  a  more  robust  form  with  large  wedge-obovate, 
jagged  leaflets,  and  large  flowers  on  long  pedicels. 


ROSACEA  357 

RASPBERRIES 

There  are  four  well-known  groups  of  cultivated  rasp- 
berries: black-cap,  purple-cane,  American  red,  and  European 
red.  . 

Key  to  Principal  Species  of  Raspberries 

Fruit  purple-black,   rarely  yellow;    propagating  by   tips,     R.    occidentalis 

(black-cap). 
Fruit  purple,  dark  red,  light  red,  or  sometimes  yellow;  propagating  by  tips 
or  suckers. 
Stems  stiflf  and  erect;  fruit  produced  more  or  less  continuously  throughout 

the  season,  R.  idaus  (European  red). 
Stems  more  slender  and  drooping;  fruit  produced  less  continuously  through- 
out the  season. 
Stems  bristly,  not  glaucous;  fruit  light  red;  inflorescence  racemose,  R. 

strigosus  (American  red). 
Stems  prickly,  slightly  glaucous;  fruit  dark  red;  inflorescence  racemose- 
cymose,  R.  strigosus  X  R-  occidentalis  (purple-cane). 

Rubus  occidentalis. — The  slender  stems  are  often  lo  to  12  feet  long,  rooting 
at  the  tip,  sparingly  supplied  with  small  hooked  prickles,  and  sometimes  glan- 
dular-bristly above.  The  leaves  are  trifoliate,  stipulate,  with  oval  or  acumi- 
nate, toothed  leaflets,  that  are  white-hairy  on  the  under  side.  The  inflor- 
escences are  dense,  and  corymbose.  The  flowers  are  on  short  pedicels;  the 
petals  are  shorter  than  the  sepals.  The  black-cap  raspberries  are  the  most 
important  in  this  country.  The  species  is  found  throughout  eastern  United 
States,  northward  into  Quebec  and  Ontario,  and  westward  to  Oregon  and 
British  Columbia. 

Some  of  the  western  forms  have  been  given  distinct  specific  names  {R.  leu- 
codermis,  R.  glaucifolius,  R.  bernardinus. 

Rubus  idaeus. — The  stems  are  stiff  and  erect,  and  furnished  with  prickles; 
glandular  bristles  are  never  present  except  in  some  cultivated  forms  which 
may  be  considered  as  hybrids  between  R.  idcsus  and  R.  strigosus;  pubescence 
occurs  on  peduncles,  pedicels,  petioles  are  nearly  always  flattened  and  slightly 
curved.  The  thick  leaves  are  white-downy  beneath.  The  fruit  is  purple  or 
yellow  and  is  produced  throughout  the  season.  The  European  raspberry  is 
not  cultivated  to  any  extent  in  this  country  at  the  present  time.  It  is  a  native 
of  Europe  and  Asia. 

Rubus  strigosus. — ^The  stems  are  slender  and  bear  stiff,  straight  or  hooked 
prickles;  glandular  bristles  occur  on  peduncles,  pedicels,  petioles,  and  calyx. 
The  leaves  are  three-  to  five-foliate,  with  ovate  or  oblong-ovate,  sharply  serrate 


358  BOTANY  OF  CROP  PLANTS 

or  lobed  leaflets,  which  are  whitish-pubescent  beneath.  The  inflorescences 
are  terminal  or  axillary,  and  racemose;  the  flowers  are  white.  The  fruit  is 
light  red,  rarely  yellow,  and  is  not  produced  continuously  throughout  the 
season.  Rubus  strigosus  is  the  native,  common  red  raspberry.  It  is  dis- 
tributed from  North  Carolina  to  New  Mexico,  northward  in  the  Rocky 
Mountains  to  Manitoba  and  British  Columbia: 'and  eastward  to  Newfound- 
land and.Labrador.     Cuthbert  is  one  of  the  principal  varieties. 

Rubus  strigosus  X  R.  occidentalis  (R.  neglectus). — The  stems  are  long  and 
often  rooting  at  the  tip,  glaucous,  prickly,  and  bristly.  The  inflorescence  is 
racemose-cymose  and  has  short,  erect  or  ascending  peduncles.  The  fruit 
varies  in  color  from  purple-black  to  bright  purple,  and  sometimes  yellow. 
Shaffer  and  Columbian  are  the  chief  varieties. 

The  Loganberry. — This  is  a  rather  notorious  fruit  that  has  resulted  from 
crossing  a  blackberry  and  a  raspberry.  It  is  supposed  that  the  blackberry 
was  the  variety  Aughinbaugh  and  the  raspberry.  Red  Antwerp.  Aughin- 
baugh  is  a  pistillate  variety  of  R.  vitifolius.  Evidence^  has  recently  been 
presented  tending  to  show  that  the  loganberry  has  behaved  as  a  true  species, 
and  is  not  a  hybrid.  The  loganberries  are  large,  often  i  to  i^  inches  long, 
and  of  a  rich,  dark  red  color,  but  unfortunately  not  of  very  superior  flavor. 

Mayberry. — This  is  supposed  to  be  a  cross  between  a  Japanese  species, 
Rubus  micro phyllus  and  Cuthbert,  a  variety  of  Rubus  strigostis. 


FRAGARIA  (Strawberry) 

Roots  and  Stems. — Strawberries  are  low,  perennial  plants 
with  very  short,  thick  stems  set  close  to  the  surface  of  the 
ground.  Such  very  short-stemmed  plants  are  usually 
termed  "acaulescent."  The  branches  that  arise  from  the 
axils  of  the  closely  set  leaves  are  called  "runners."  Runners 
are  slender  stems,  growing  along  the  ground  surface;  they 
have  long  internodes,  and  produce  leaves  and  flowers  and 
roots  at  the  nodes.  Runners  are  used  as  a  means  of  propa- 
gating the  plant.  They  are  attached  to  the  old  plant  for 
but  one  season.  In  the  Virginian  group  of  strawberries,  the 
runners  start  to  form  as  early  as  new  leaves  are  produced  and 
may  attain  a  considerable  length  before  the  fruit  is  mature. 
In  the  Chilean  group,  the  runners  a-re  usually  formed  after 

^  journal  of  Heredity,  7:  504-507,  1916. 


ROSACE.E  359 

the  fruit  is  matured.  Runners  may  branch.  New  branches 
from  the  main  perennial  stem  appear,  of  course,  above  the 
old  ones,  hence  there  is  a  tendency  for  the  short  stem  to 
become  more  and  more  exposed  above  the  ground  surface.. 
Roots  do  not  extend  over  a  depth  of  2  feet  in  the  soil,  and 
horizontally,  scarcely  beyond  the  area  covered  by  the  leaves. 
Practicallv  all  roots  arc  within  the  first  foot  of  soil. 


,cif  .slra\v!)crry  (Frai;aria  cliilnoiisis).      A1j'A-c.  iwu  i)crfcct, 
ilowLTs;  below  two  pistillate  llowers. 

Leaves." — The  leaves  are  alternate  and  arise  in  a  tuft;  the 
petioles  are  usually  much  longer  than  the  leaf  blades,  which 
are  divided  into  three  leaflets  (trifoliate);  sheathing,  mem- 
branous, adnate  stipules  which  increase  in  size  as  the  leaf 
grows,  occur  at  the  base  of  the  petiole. 

Inflorescence  and  Flowers. — The  white  tlowers  are  in 
small    racemes    or    corymbs  on   long,   erect,    leafless  scai)es 


360 


BOTANY   OF   CROP    PLANTS 


which  spring  from  the  crown  of  the  plant.  The  flowers  are 
usually  perfect;  however,  there  are  some  varieties  (Bisel, 
Princess,  Warfield,  etc.)  which  have  only  pistillate  flowers 
.(Fig.  150);  there  are  no  commercial  varieties  that  have  only 
staminate  flowers.  In  planting  varieties  with  pistillate 
flowers  only,  it  is  necessary  to  have  rows  near-by  planted  to 
pollen-bearing  individuals.     Some  perfect-flowered  varieties 


stamens 


\^^rim  of  receptacle 
^jleshxj  receptacle 


Fig.    151. — Strawberry  (Fratjaria  chilueiisis).      Median  lengthwise  section  of 
flower.      X  4. 


(Glen  Mary  and  Crescent)  bear  very  few  stamens,  and  hence 
are  practically  self-sterile.  The  receptacle  is  convex  or  con- 
ical (Fig.  151).  The  caly.x  is  live-parted,  with  Ave  bracteoles 
(epicaly.x)  below,  that  ^are  persistent  in  the  fruit.  There 
arc  live  obovate,  short-clawed  petals,  attached  to  the  rim  of 


ROSACEA  361 

the  receptacle.  There  are  numerous  stamens,  as  a  rule, 
sometimes  a  few  or  none;  they  are  attached  to  the  rim  of  the 
receptacle,  persistent  in  the  fruit,  and  possess  slender  fila- 
ments and  small  anthers.  Pistils  are  numerous  on  the 
smooth,  convex,  or  conical  receptacle  which  becomes  modi- 
fied m  the  fruit  (Fig.  152,  A).  Each  carpel  bears  a  style 
laterally  placed  (Fig.  152,  B),  and  a  single  ovule. 

Fertilization,  and  Development  of  the  Fruit.— Strawberries 
are  protogynous,  that  is,  the  pistils  of  a  flower  mature  before 
its  stamens.  Hence  cross-fertilization  is  secured;  and  this 
usually  by  insects.  Non-fertilization  or  incomplete  fertili- 
zation is  usually  indicated  by  berries  with  hard,  greenish, 
undeveloped  apices,  so-called  "nubbins."  The  true  fruits 
of  a  strawberry  are  the  achenes  (so-called  "seeds")  scattered 
over  the  fleshy  receptacle.  Unless  the  ovules  are  fertilized, 
the  receptacle  does  not  mature  properly.  This  behavior  is 
the  rule  in  most  plants.  When  a  sperm  nucleus  of  the  pollen 
tube  unites  with  the  egg  nucleus  of  the  ovule,  resulting  in 
fertilization,  there  is  set  into  action  a  train  of  changes  which 
not  only  involve  the  ovule  itself,  but  which  extend  to  the 
ovary  wall,  and,  as  in  the  strawberry,  to  the  receptacle. 
Undoubtedly,  the  stimuli  are  chemical  in  nature,  but  just 
what  they  are  and  how  they  act  is  not  known. 

The  Mature  Fruit. — The  strawberry  "fruit"  (popularly 
speaking)  is  an  aggregate  of  true  fruits.  The  fleshy  part 
of  the  "fruit"  is  receptacle,  while  the  true  fruits  (botanically 
speaking)  are  achenes  partially  imbedded  in  the  surface  of 
the  receptacle.  In  a  lengthwise  section  (Fig.  152,  A)  of  the 
ripened  fruit,  the  receptacle  is  seen  to  be  composed  of  a 
fleshy  pith  and  cortex  with  fibro-vascular  bundles  between 
them.  It  is  in  reahty  stem  structure.  These  bundles  send 
off  side  branches  into  the  cortex,  and  some  of  them  extend 
to  the  achenes.     The  persistent  calyx  and   epicalyx,    and 


362 


BOTANY   OF   CROP  PLANTS 


withered  stamens  are  at  the  base  of  the  fruit.  These  con- 
stitute the  "hull"  of  the  fruit.  The  achenes  are  attached  to 
the  receptacle  a  short  distance  above  their  base  and  the 
styles  arise  from  the  ventral  side,  a  little  above  the  point  of 


corfex  of 
idle 


medulla  of 
receptacle 


Fig.   152. — Strawberry  (Fragaria  chiloensis).     A,  "frviit"  in  median  length- 
wise section,  X  2>^;  B,  single  achene,  X  20. 


The  achenes  are  com- 


attachment  of  fruit  to  receptacle, 
monly  termed  "seeds." 

Geographical. — The  genus  Fragaria  possesses  about  eighteen  species  most 
of  which  are  natives  of  the  north  temperate  zone;  a  number  are  found  in 
the  Andes  of  South  America.  Strawberries  are  cultivated  in  all  parts  of 
the  United  States. 


ROSACEA  ■  363 

Principal  Fruit-bearing  Species.— The  evolution  of  the 
strawberry  has  been  given  to  us  by  Bailey.  Most  of  our 
cultivated  varieties  of  strawberries  belong  to  the  species 
Fragaria  chiloensis.  This  plant  is  a  native  of  western  Chile, 
from  which  country  it  was  brought  to  Europe  at  the  begin- 
ning of  the  eighteenth  century.  The  Chilean  strawberry  is 
also  a  native  of  the  western  coast  region  of  North  America, 
as  well  as  of  South  America.  However,  some  botanists 
would  refer  the  forms  as  found  in  this  continent  to  the  species 
Fragaria  calif  ornica  and  F.  glauca. 

The  early  settlers  in  the  Eastern  States  cultivated  the 
common  wild  strawberry  {Fragaria  virginiana)  which  they 
found  growing  in  their  fields.  But  few  cultivated  varieties 
belong  to  it.  Varieties  of  the  wild  strawberry  of  Europe 
{Fragaria  vesca)  have  also  been  cultivated  in  America,  but 
only  to  a  slight  extent.  These  varieties  are  the  Everbearing 
or  Perpetual  strawberries. 

Hence,  the  varieties  of  strawberries  in' America  fall  into 
three  groups,  as  follows: 

1.  Chilean  group  from  Fragaria  chiloensis. 

2.  Scarlet  or  Virginian  group  from  Fragaria  virginiana. 

3 .  Perpetual  or  European  group  from  Fragaria  vesca. 
These  three  species  may  be  distinguished  by  the  following 

key: 

Key  to  PiaNCiPAL  Species  of  Fragaria 

Leaves  usually  projecting  above  the  flowers  and  fruit;  achenes  sunken  in  the 
flesh. 
Runners  appearing  after  the  fruit;  berry  dark;  calyx  large;  leaves  shining 

above,  bluish- white  beneath,  F.  chiloensis  (Chilean  strawberry). 

Runners  appearing  with  the  fruit;  berry  scarlet;  calyx  medium;  leaves  light 

green  on  both  surfaces,  F.  virginiana  (scarlet  or  Virginian  strawberry). 

Leaves  usually  not   projecting   above  the  flowers   and  fruit;   achenes   not 

sunken  in  the  flesh,  F.  vesca  (perpetual  or  European  strawberry) . 

Fragaria  virginiana  (Virginia  or  Scarlet  Strawberry). — ^This  is  a  stout,  dark 


364  BOTANY   OF   CROP   PLANTS 

green,  tufted  herb  with  soft-hairy  leaves.  The  petioles  are  from  2  to  6  inches 
long,  the  leaflets  oval  or  obovate,  obtuse,  dentate,  the  lateral  not  symmetrical 
at  the  base.  The  scape  is  usually  shorter  than  the  leaves,  at  least  not  exceed- 
ing them,  hence  the  fruits  are  borne  below  the  leaves.  The  calyx  lobes  are 
erect  at  maturity.  The  fruit  is  red,  ovoid,  and  with  achenes  imbedded  in  the 
flesh. 

The  species  extends  from  New  Brunswick  to  South  Dakota,  south  to  Florida, 
Louisiana  and  Arizona. 

Fragaria  vesca  {European  Wood  or  Everlasting  Strawberry). — ^This  is  a  stout, 
dark  green,  tufted  plant  with  hairy  leaves.  The  leaflets  are  ovate  or  broadly 
oval,  obtuse,  dentate,  the  lateral  not  symmetrical  at  the  base.  The  scape  is 
longer  than  the  leaves,  hence  the  fruits  are  borne  above  the  leaves.  The  calyx 
lobes  are  spreading  or  reflexed.  The  fruit  is  red,  hemispheric  or  conic,  with 
achenes  not  imbedded  in  the  flesh. 

This  strawberry  is  a  native  of  Europe,  but  naturalized  in  the  Eastern  and 
Middle  States.     It  has  given  us  our  Perpetual  and  Ever  bearing  varieties. 

Fragaria  chiloensis  (Chilean  Strawberry). — The  Chilean  strawberry  is  a  low 
form  with  thick  leaves,  shining  above  and  bluish-white  beneath;  the  runners 
appear  after  the  fruit  is  gone.  The  fruit  is  large,  firm,  dark,  with  a  large 
"hull,"  and  with  achenes  sunken  in  the  flesh. 

It  is  a  native  of  the  western  coasts  of  South  America  and  North  America. 
Most  of  the  common  varieties  of  strawberries  belong  to  the  Chilean  species. 

Varieties. — The  number  of  varieties  of  strawberries  is  great. 
They  are  commonly  divided  into  three  groups  as  to  time  of 
maturing:  first,  early  (Warfield,  Excelsior,  Bederwood); 
second,  medium  (Ridgeway,  Dunlap,  Marshall,  Jucunda); 
and  third,  late  (Aroma,  Gandy,  Chesapeake,  Splendid). 
Growers  distinguish  between  commercial  varieties  and  those 
for  home  consumption.  A  good  commercial  variety  should 
be  hardy,  very  productive,  of  good  color,  firm,  and  of  good 
size  and  form.  Among  good  commercial  varieties,  may  be 
mentioned  Bederwood,  Excelsior,  Jucunda,  Dunlap,  Captian 
Jack,  Splendid,  and  Parson's  Beauty.  Such  varieties  as 
Warfield,  Ridgeway,  Marshall,  Aroma,  and  Chesapeake  are 
grown  for  home  use. 

Origin  of  New  Varieties. — Strawberries  seldom  come  true 
to  seed;  hience  it  is  possible  to  secure  new  varieties  by  plant- 


ROSACEA  365 

ing  seed.  When  a  desirable  variation  appears,  propagatejt 
and  keep  it  "true"  by  means  of  runners.  This  method  of 
vegetative  propagation  insures  permanency  in  the  characters 
of  the  variety  selected. 

Uses. — Strawberries  are  used  chiefly  in  the  fresh  state. 
There  is  an  increasing  demand  for  such  strawberry  products 
as  crushed  fruit,  preserves,  marmalades,  and  jellies.  Large 
quantities  are  put  up  fresh  for  use  at  soda  fountains  and  in 
the  manufacture  of  ice  cream. 

References 

Bailey,  L.  H.:  Survival   of    the    Unlike.     Essay    25,    Strawberries,  The 

MacMillan  Co.,  1896. 
Blanchard,  W.  H.:  Rubus  of  Eastern  N.  A.     Bull.  Torrey  Bot.  Club,  38: 

425-439,  iQii- 
BuNYARD,  E.  A.:  The  History  and  Development  of  the  Strawberry.     Jour. 

Hort.  Soc,  39:  541-552,  1914- 
CoRBETT,  L.  C:  Strawberries.     U    S.  Dept.  Agr.  Farmers' Bull.  198:  1-24, 

1904. 


CHAPTER  XXVII 
POMACES  (Apple  Family) 

Habit,  Leaves. — Members  of  the  apple  family  are  either 
trees  or  shrubs.  The  alternate  simple  or  compound  leaves 
are  petioled,  and  have  small  deciduous  stipules. 

Inflorescence. — The  inflorescences  are  racemose  {Amel- 
ancJner,  service-berry),  cymose  {Malus,  apple,  Sorbus,  moun- 
tain ash)  or  simple  {Cotoneaster,  evergreen  or  fire  thorn). 

Flowers. — The  flowers  (Fig.  157)  are  regular,  perfect,  and 
usually  with  a  concave  or  cup-shaped  receptacle  or  torus  to 
which  is  attached  a  five-lobed  or  five-toothed  calyx,  five  sepa- 
rate petals,  numerous  distinct  stamens  and  a  one-  to  five- 
celled  ovary.  The  ovary  is  ordinarily  five-celled,  and  the 
carpels  are  wholly  or  partly  united.  The  carpels  vary  in 
texture  from  parchment-like  (Malus,  etc.)  to  bony  (CratcB- 
%us  and  Cotoneaster).  The  number  of  styles  varies  in  the 
different  genera:  generally  three  in  Sorbus,  two  to  five  in 
Malus  (usually  five),  mostly  five  in  Pyrus  (pear),  two  to  five 
in  Amelanchier,  one  to  five  in  Cratcegus  (thorn  apples),  two 
to  five  in  Cotoneaster.  They  may  be  distinct,  as  in  Sorbus, 
or  partly  united  as  in  Malus.  The  ovules  are  commonly  two 
{Malus)  in  each  cell,  sometimes  one  {Amelanchier),  or  rarely 
several  {Cydonia,  quince). 

Fruit. — The  fruit  is  a  pome.  Representatives  of  the 
family  are  commonly  spoken  of  as  "pomaceous. "  The  pome 
is  a  false  or  spurious  fruit  in  which  the  receptacle  or  torus  be- 
comes fleshy,  to  form  the  greater  portion  of  the  fruit,  and 
encloses  five  bony,  leathery  or  papery  carpels  (Fig.  158). 
366 


POMACES  367 

Geographical. — The  family  is  of  wide  geographical  distribution,  there  being 
dose  to  225  species  within  about  20  genera.  Most  of  the  species  occur  in 
north  temperate  or  boreal  regions. 

Key  to  Import.vnt  Genera  of  Pom.vce.e 

Ripe  carpels  bony,  Cralcegus  (thorn-apple,  haw,  hawthorn). 
Ripe  carpels  papery  or  leathery. 
Leaves  compound,  Sorbus  (mountain  ash). 
Leaves  simple. 

Ovules  one  in  each  cavitj^,  Amdanchicr  (service-berry,  June-berry). 
Ovules  (usually)  two  in  each  cavity. 

Flesh  of  the  pome  with  grit-cells,  Pynis  (pear). 
Flesh  of  the  pome  without  grit-cells.  Mains  (apples  and  crab-apples). 
Ovules  many  in  each  carpel,  Cydonia  (quince). 

MALUS  (Apples) 

Stems. — Malus  species  are  either  trees  or  shrubs.  In  the 
apple,  all  rapid-growing  shoots  develop  only  leaf  buds. 
Flower  buds,  which  in  the  apple  are  "mixed"  buds,  are  al- 
most always  borne  on  the  ends  of  ''spurs"  or  short  twigs. 
When  a  "spur"  terminates  in  a  flower  bud,  lateral  buds  lower 
down  continue  the  growth  of  the  shoot,  hence  the  crooked 
appearance  of  such  spurs  (Fig.  153).  These  lateral  buds 
may  grow  for  a  year  or  so,  bearing  leaf  buds  at  the  terminus, 
and  then  be  stopped  in  their  growth  in  that  direction  by  the 
formation  of  a  terminal  flower  bud.  As  a  rule,  a  shoot  that 
has  once  started  to  bear  flowers  continues  to  do  so,  making 
but  a  very  short  growth  of  wood  each  year.  Such  a  shoot  is 
marked  by  the  closely  crowded  leaf  scars,  terminal-bud  scars, 
and  flower  and  fruit  scars.  The  position  of  a  fruit  is  usually 
marked  by  a  large  circular  scar  surrounded  by  a  number  of 
smaller  ones  of  the  same  shape.  The  smaller  ones  represent 
scars  made  by  flowers  or  fruit  that  failed  to  develop.  It  has 
been  recorded  generally,  particularly  for  Eastern  orchards, 
that  the  fruit  buds  in  apples  are  always  terminal,  and  further- 


368 


ROTANY    OF    CROP    PLANTS 


more  that  the  fruit  spur  must  be  two  or  more  years  old  before 
it  will  bear  fruit.     Paddock  and  Whipple  ("Fruit  Growing  in 


Fig.    153. — Spur  of  Yellow  Transparent  apple. 

Arid  Regions")  have  noted  that  in  certain  districts  of  Colo- 
rado many  varieties  produce  flower  buds  in  the  axils  of  leaves 
on  the  growth  of  the  current  season  and  that  one-year-old  spurs 


POMACEiE 


369 


may  in  many  instances  bear  fruit  (Fig.  154),  or  that  fruit  may 
be  borne  at  the  end  of  last  year's  terminal  growths,  not  spurs. 
Hyslop,  Mann,  Missouri  Pippin,  Strawberry,  Striped,  Trans- 
cendent and  Winesap  are  among  those  varieties 
producing  fruit  in  the  axils  of  leaves.  Astra- 
chan,  Ben  Davis,  Grimes,  Hyslop,  Jonathan, 
Mcintosh,  Missouri  Pippin,  Newton,  Northern 
Spy  are  a  few  varieties  found  to  be  bearing  fruit 
on  one-year-old  spurs.  A  few  varieties  such  as 
Grimes,  Hyslop,  Transcendent,  Willow  Twig, 
and  Yellow  Transparent  produce  fruit  on  the 
end  of  last  year's  terminal  growths,  not  spurs. 

Gourley  has  observed  axillary  fruit  buds 
throughout  the  Eastern  States  on  both  old  and 
young  trees,  and  in  many  varieties.  Different 
forms  of  fruit  branches  occur;  furthermore  the 
same  variety,  or  even  tree,  may  bear  more  than 
one  sort  of  fruit  branch.  Frequently,  it  has 
been  noted  that  spurs  bear  annually,  instead 
of  biennially,  as  is  the  rule.  In  such  a  case, 
fruit  buds  are  developing  on  a  spur  at  the  same 
time  that  an  apple  is  maturing. 

It  is  not  always  an  easy  matter  to  distinguish 
between  the  fruit  and  leaf  buds  of  apple. 
Generally,  fruit  buds  are  rather  thick  and 
rounded,  while  leaf  buds  are  smaller  and  more 
pointed. 

It  has  been  shown  that  fruit  buds  are  differ- 
entiated very  early,  and  may  be  distinguished 
by  microscopic  study,  from  leaf  buds,  as  early  as  the  last 
week  in  June  of  the  year  preceding  the  opening  of  the  flower. 
The  above  has  been  reported  by  Drinkard,  and  Kraus  has 
observed  that  in  the  Yellow  Newton  apple,  under  Oregon 
24 


Fig.  IS4-— 
Mature  Jona^ 
than  apples 
from  axillary 
flower  buds. 
{After  Pad- 
dock and 
Whipple.) 


370  BOTANY  OF  CROP  PLANTS 

conditions,  the  fruit  and  leaf  buds  are  differentiated  in  early 
July,  and  in  early  varieties,  even  by  the  latter  part  of  May. 

The  form  of  the  tree,  nature  of  twigs,  branches,  bark  and 
leaves  vary  a  great  deal  in  the  many  varieties  of  apples. 

Leaves. — These  are  simple,  alternate,  and  toothed  or 
lobed;  the  stipules  are  free  from  the  petiole. 

Inflorescence. — It  will  be  recalled  that  the  buds  contain- 
ing flowers  are  mixed  buds.  Hence,  when  each  opens  there 
is  developed  a  very  short  axis  bearing  closely  crowded  leaves 
and  flowers.  On  this  axis,  the  flowers  are  apical,  the  leaves 
basal.  The  flowers  may  be  so  crowded  that  the  cyme  is 
umbel-like  in  appearance.  In  most  cases,  the  inflorescence 
is  terminal,  but,  as  has  been  indicated  above,  it  is  axillary 
in  some  varieties.  The  number  of  flowers  in  a  single  mixed 
bud  may  vary  from  two  or  three  to  eight  or  ten.  As  a  rule, 
but  one  flower  matures  its  fruit,  thus  illustrating  the  struggle 
for  existence  among  the  different  individual  flowers. 

The  determinate.inflorescence,  cyme,  of  apple  is  not  always 
definitely  so.  It  will  be  remembered  that  in  the  cyme  type 
of  inflorescence  the  flowers  open  in  order  from  the  inside 
outward.  Sometimes  the  central  flower  is  tardy  in  its 
development,  and  often  the  central  and  some  of  the  laterals 
may  open  simultaneously. 

Flowers  and  Their  Development. — The  development  of 
the  apple  flower  (Yellow  Newton)  has  been  worked  out  by 
Kraus.  A  longitudinal  section  (Fig.  155)  of  a  growing  axis 
shows  a  number  of  bracts  and  bud  scales  surrounding  it;  on 
the  sides  of  the  axis,  appear  the  primordia  of  flower  buds  and 
leaves.  The  primordia  of  sepals  are  the  first  to  appear. 
The  torus  develops  especially  toward  the  outer  edge  by  a 
growth  of  the  cells  beneath  the  developing  calyx,  and  finally 
takes  on  a  concave  shape.  The  torus  continues  to  uprise 
during  the  development  of  petals  and  stamens,  both  of  which 


POMACES 


371 


are  seen  to  arise  from  the  concave  sides  of  the  torus.  Follow- 
ing the  appearance  of  sepal  primordia,  appear  petal  primor- 
dia,  then  those  of  stamens,  and  lastly  those  of  the  carpels. 
The  succession  of  floral  cycles  is  acropetal,  i.e.,  in  order 
from  without  to  the  inside. 


Fig.   155. — Diagram  showing  the  development  of  apple.     Dotted  area  repre- 
sents pith.     Not  drawn  to  scale.     {After  Kraus,  Oregon  Agr.  Exp.  Sla.) 


The  primordia  of  stamens  appear  in  three  cycles,  those  of 
the  outer  usually  being  laid  down  first  (Fig.  156).  The  carpel 
primordia  appear  within  the  central  portion  of  the  cup-shaped 
torus.  There  are  five  of  these  surrounding  a  small  central 
cavity,  which  is  formed  by  a  lack  of  growth  at  the  center  of 
the  torus.  Hence  there  is  no  common  placenta,  but  each 
carpel  has  its  two  separate  placentas,  which  in  "open-cored" 
pomes  may  become  closely  connected.  These  facts  will  be 
considered  again  in  the  account  of  fruit  development. 

It  is  thus  shown  by  the  studies  of  Kraus  that  calyx  lobes, 
petals,  stamens,  and  carpels  are  all  outgrowths  of  the  urn- 
shaped  receptacle. 


372  BOTANY  OF  CROP  PLANTS 

Pollination  and  Fertilization. — The  literature  on  this 
subject  is  extensive.  Cross-pollination  is  the  rule  and 
self-polHnation  the  exception  in  the  apple  and  pear.  Ex- 
periments have  shown  that  the  wind  aids  but  Httle  in  cross- 
polhnation,  and  that  insects,  chiefly  the  honey  bee,  are 
relatively  more  important  The  bee  is  attracted  to  the 
flowers  by  the  nectar  which  is  produced  rather  abundantly. 


Fig.  156. — Floral  diagram  of  apple  (Malus  sylvestris).     Note  that  the  sta- 
mens are  in  three  distinct  whorls.     {After  Kraus.) 


Self -sterility  and  Self -fertility.- — Many  apples  and  pears 
are  self-sterile,  that  is,  will  not  fertilize  their  own  pistils. 
In  such  cases,  pollen  from  another  variety  will  usually  result 
in  fertilization.  Self-steriHty  and  self-fertility  probably 
vary  with  different  climatic  conditions.  In  Oregon,  Lewis 
and  Vincent  found  that  the  Spitzenburg  is  self-sterile  but 
capable  of  being  fertiUzed  with  pollen  from  a  number  of  other 
varieties,  such  as  Yellow  Newton,  Arkansas  Black,  Jonathan, 
and  Baldwin.  Evidently,  the  mutual  affinities  of  apple 
varieties  must  be  considered  in  setting  out  an  orchard.  It 
would  not  be  well  to  plant  soHd  blocks  of  Spitzenburg,  for 
example.     It  should  be  alternated  with  rows  of  some  one  of 


POMACES 


373 


the  other  varieties  the  pollen  of  which  is  capable  of  fertilizing 
it.  It  is  no  doubt  true  that  the  failure  of  many  varieties  to 
set  fruit  is  due,  in  part,  to  self-sterility. 

Effects  of  Strange  Pollen. — The  secondary  effects  of  for- 
eign pollen  on  the  mature  fruit  have  received  considerable  at- 
tention. It  is  claimed  by  many  that  the  pollen  from  one  va- 
riety when  placed  on   the  stigma  of  another,  immediately 


Fig.  157. — Apple     (Malus 


sylvestris).     Median 
flower. 


longitudinal     section     of 


impresses  its  characteristics  upon  the  fruit.  It  is  difficult  to 
understand  how  foreign  pollen  could  have  any  considerable 
effect  of  this  kind.  The  flesh  of  the  apple  is  receptacle  for  the 
most  part.  The  sperm  nuclei  of  the  pollen,  of  course,  do  not 
come  into  contact  with  the  nuclei  of  the  receptacle  cells.  It  is 
altogether  possible,  however,  that  uniformity  of  crop,  percent- 
age of  set,  and  size  of  fruit  are  immediately  affected  by 
strange  pollen. 


374  BOTANY  OP  CROP  PLANTS 

Parthenocarpy. — As  a  general  rule,  lack  of  fertilization  of 
the  ovules  in  the  ovary  is  followed  by  the  shedding  of  the 
blossoms;  the  ovary  fails  to  develop  completely  if  a  good 
number  of  its  ovules  are  not  fertilized.  However,  develop- 
ment of  the  ovary  does  sometimes  occur  although  fertiliza- 
tion fails.  Such  an  unusual  development  of  carpels  is  called 
parthenocarpy.  This  phenomenon  is  not  unknown  in  the 
apple.  With  certain  sorts  of  both  apples  and  pears,  fruits 
weighing  loo  grams  have  been  developed  without  fertiliza- 
tion. Of  course,  parthenocarpic  fruit  is  seedless.  There  are 
among  cultivated  plants  many  which  bear  seedless  fruit. 
We  noted  that  in  the  common  Mission  figs  the  fruit  matures 
normally  without  fertilization  of  the  ovules.  Seedless  to- 
matoes, egg  plants,  English  forcing  cucumbers,  oranges, 
grapes,  and  bananas  are  quite  common. 

The  Fruit  and  Its  'DQveloi^m.Qnt— Morphology. — There 
are  two  common  opinions  as  to  the  nature  of  pomaceous 
fruits: 

1.  Flesh  is  thickened  calyx  tube. 

2.  Flesh  is  receptacle  or  torus  closely  connected  with  the 
carpels. 

The  recent  work  of  Kraus  appears  to  establish  the  latter. 
In  following  through  the  development  of  the  flower  (Fig. 
155),  it  is  seen  that  the  receptacle,  by  more  rapid  growth  at 
the  sides  than  toward  the  center,  becomes  urn-shaped  and 
bears  on  the  rim  and  inside  face,  calyx  lobes,  petals,  and 
stamens.  In  the  development  of  the  fruit,  there  is  a  con- 
tinuation of  the  enlargement  of  the  receptacle ;  the  throat  of 
the  receptacle  becomes  narrow,  and  through  it  the  styles  pro- 
trude; and  the  connection  between  receptacle  and  carpel 
tissues  becomes  a  very  close  one;  hence  receptacle  makes  up 
the  greater  portion  of  the  flesh  of  the  apple. 

Ripening  Process. — Important  chemical  changes  take  place 


POMACES  375 

in  the  ripening  process.  The  content  of  sucrose  (cane  sugar) 
increases  steadily  in  the  ripening  process  up  to  a  maximum 
and  then  suddenly  decreases.  There  is  a  rapid  decrease  of 
starch  throughout  the  entire  period.  Invert  sugar  (a  mix- 
ture of  glucose  and  fructose)  increases  throughout  the  ripen- 
ing period  while  the  total  sugar  increases  up  to  the  date  when 
starch  entirely  disappears,  after  which  time  it  fluctuates 
sUghtly.  MaUc  acid,  which  gives  the  fruit  its  sourness, 
gradually  becomes  less  and  less.  Ripening  takes  place  in 
'two  stages.  The  first  stage  involves  that  portion  of  the  fruit 
within  the  core  hne  (Fig.  158).  Here  there  is  at  first  a  de- 
crease in  the  starch  content  just  between  the  locules,  at  the 
tips  of  the  carpels.  This  loss  extends  outward  from  these 
points  to  the  core  Hne.  The  second  stage  of  the  ripening  proc- 
ess involves  the  region  outside  the  core  line.  At  first, 
streaks  free  of  starch  appear  in  the  midst  of  this  area.  Soon 
the  middle  portion  of  the  area  becomes  free  of  starch.  There 
is  a  gradual  increase  of  this  starch-free  area,  the  last  regions 
to  ripen  being  V-shaped  areas  radiating  from  the  vascular 
bundles  as  seen  in  cross-section.  Furthermore,  anatomical 
changes  take  place  in  ripening.  The  middle  lamellae  of  the 
cells  soften,  resulting  in  a  slight  separation  of  the  cells,  an 
increase  in  the  regularity  of  the  cell  outline,  in  the  size  of 
intercellular  spaces,  and  amount  of  intercellular  air. 

'^Mealiness." — This  results  from  a  softening  of  the  middle 
lamellae;  those  varieties  that  are  comparatively  very  mealy 
have  correspondingly  weak  lamellae.  When  a  cell  divides 
into  two,  the  common  primary  wall  between  them  becomes 
the  middle  lamella  of  the  thicker  wall  formed  by  the  deposi- 
tion of  material  from  both  protoplasts.  Hence  in  the  mature 
cell  wall,  the  primary  or  first-formed  wall  appears  as  a  defi- 
nite layer  between  the  added  layers.  Separation  of  two  ad- 
jacent cells  naturally  takes  place  along  this  middle  Hne. 


376 


BOTANY   OF   CROP   PLANTS 


POMACES  377 

Cross-section  of  Fruit. — In  a  median  cross-section  of  the 
apple  fruit  (Fig.  158),  the  relation  of  carpels  and  receptacle  is 
well  made  out.  The  five  carpels  radiate  from  the  center. 
Each  carpel  is  composed  of  a  parchment-like  endocarp, 
fleshy  mesocarp,  and  fleshy  exocarp.  The  pith  of  the  re- 
ceptacle, which  is  in  reality  stem,  surrounds  and  unites 
with  the  carpels;  the  pith  is  without  vascular  bundles.  As  a 
rule,  there  are  ten  primary  vascular  bundles  seen  in  the 
median  cross-section.  They  mark  the  limits  of  the  pith,  all 
tissue  outside  of  them  being  cortex  of  the  receptacle. 

The  tissues  of  the  carpels  and  pith  are  very  similar.  How- 
ever, the  tissue  of  the  carpels  bears  a  network  of  very  fine 
vascular  bundles,  while  that  of  pith  is  without  such  a  network. 
Many  observers  have  wrongly  considered  all  tissue  from 
parchment-like  tissue,  surrounding  the  seed  cavities,  out  to 
vascular  ring,  inclusive,  as  carpellary,  whereas  others  have 
considered  only  the  parchment-like  tissue  as  carpellary. 

The  ten  primary  vascular  bundles  are  related  in  their 
development  with  the  carpels,  as  is  shown  by  the  fact  that 
when  six  carpels  occur  there  are  twelve  bundles  instead  of 
ten,  and  when  there  are  four  carpels,  eight  bundles. 

Longitudinal  Section  of  Fruit. — In  longitudinal  section 
(Fig.  158),  the  flesh  is  seen  to  be  separated  into  two  parts  by 
a  distinct  fine,  the  "core  Hne."  The  core  line  marks  the 
junction  of  pith  and  cortex  of  the  receptacle.  The  primary 
vascular  bundles  of  the  torus  follow  the  core  line,  and 
branches  from  them  spread  out  into  the  cortex  of  the  fruit. 
Kraus  has  demonstrated  that  apple  varieties  show  marked 
variation  in  their  internal  structure,  and  that  this  structure 
is  distinctive  for  any  given  variety. 

External  Characteristics. — These  are  very  important  in 
technical  descriptions  of  the  apple.  Form  is  of  considerable 
consequence.     In  judging  form,  the  apple  is  held  so  as  to 


378  BOTANY  OP  CROP  PLANTS 

be  seen  in  a  line  at  right  angles  to  an  axis  from  stem  end  to 
calyx  end.  Form  terminology  includes  such  terms  as  round, 
oblate,  conical,  ovate,  oblong,  elliptical,  etc.  The  flower 
stem  persists  in  the  fruit.  The  depression  about  the  stem 
is  termed  the  cavity.  It  varies  in  shape  and  depth  in  the 
different  varieties.  At  the  opposite  end  from  the  cavity  is 
the  basin.  This  also  varies  in  character  and  is  of  taxonomic 
value  in  the  classification  of  fruits.  The  remains  of  the 
calyx  are  persistent  within  the  basin  of  the  common  apple. 
In  the  pure  Siberian  Crabs,  the  calyx  is  deciduous,  while  in 
hybrid  forms  of  Siberian  Crabs  and  in  the  common  apple 
it  is  partly  deciduous.  The  dried  stamens  and  styles  may 
be  seen  within  the  calyx  lobes. 

The  stamens  may  be  basal,  situated  near  the  base  of  the 
calyx  tube;  median,  near  the  middle;  or  marginal,  near  the 
outer  edge.  The  calyx  tube  itself  varies  in  shape  from  con- 
ical to  funnel-shaped.  The  calyx  segments,  five  in  number, 
vary  in  their  arrangement  in  the  mature  fruit.  They  may 
be  divergent,  that  is,  reflexed,  erect  convergent,  when  their 
margins  touch,  flat  convergent,  when  they  are  flat  and  close 
the  tube,  and  connivent,  when  they  are  overlapping.  In  a 
median  transverse  section,  the  "cells"  in  different  varieties 
vary  in  shape  and  relation  to  the  axis  of  the  apple.  They 
may  be  "open"  or  "closed,"  axile  or  abaxile.  When  the 
walls  extend  to  the  axis,  the  cells  are  axile,  and  when  they 
are  distant  from  the  axis,  and  unsymmetrical,  they  are  abaxile. 
When  the  core  line  meets  inside  the  calyx  tube,  the  core  is 
said  to  be  meeting;  if  near  the  calyx  tube,  it  is  clasping. 
The  core  outline  varies  in  shape.  There  are  usually  two 
seeds  in  each  cell  cavity;  however,  there  may  be  more  than 
two  or  fewer  or  sometimes  none  at  all.  They  vary  in  size 
and  color. 


POMACEiE  379 

Key  to  Principal  Species  of  Malus 

Calyx  deciduous  from  the  apex  of  fruit. 
Leaves  conduplicate  in  the  bud  (Fig.  loi);  petioles  thick,  usually  about  i 

inch  long;  flowers  rose-colored,  M alus  floribunda  (flowering  crab). 
Leaves  convolute  in  the  bud  (Fig.  loi);  petioles  slender,  usually  about  2  to 
3  inches  long;  flowers  white   or  very  light  rose-colored,  Malus  haccata 
(Siberian  crab). 
Calyx  persistent  on  the  fruit. 
Leaves  glabrous,  at  least  when  mature. 

Leaves    prominently    lobed,    thin,  Malus    coronaria    (American   crab- 
apple). 
Leaves    toothed,  but    not   lobed,  thick,  Malus    anguslifolia  (narrow- 
leaved  crab-apple). 
Leaves  persistently  pubescent  or  tomentose  beneath. 

Leaves  narrowed  at  base;  pomes  small,  i  to  i^  inches  in  diameter. 
Pedicels  slender,  i  to  i}4  inches  long,  Malus  ioensis  (Western  crab- 
apple). 
Pedicels   stout,    }i   to    i  inch  long,  Malus  soulardii  (Soulard  crab- 
apple). 
Leaves  rounded  or  subcordate  at  base;  pomes  large,  2  to  4  inches  in 
diameter  Malus  sylvesiris  (common  apple). 

Malus  floribunda,  Flowering  Crab. — This  is  a  shrub  or  small  tree, .often 
thorny.  The  leaves  are  conduplicate  in  the  bud,  the  flowers  abundant, 
showy,  and  rose-red,  the  fruit  red,  about  the  size  of  a  pea,  and  on  slender 
stalks.  It  is  highly  ornamental,  and  flowers  in  early  spring.  It  is  a  native  of 
Japan. 

M.  baccata,  Siberian  Crab. — This  crab  is  a  small,  spreading  tree  with  leaves 
that  are  convolute  in  the  bud,  abundant  flowers,  usually  white  and  showy,  and 
fruit  that  is  H  to  %  inch  in  diameter,  yellow  or  red,  firm  and  translucent. 
The  species  occurs  in  many  forms.  The  orchard  fruits  known  as  "crab- 
apples"  are  believed  to  be  hybrids  between  this  and  the  common  apple,  M. 
sylvesiris.  The  Siberian  crab  grows  wild  from  Siberia  to  Manchuria  and  the 
Himalaya    region. 

M.  angustifolia,  Narrow-leaved  Crab-apple. — It  is  a  low  tree  with  small, 
narrow,  lanceolate  leaves,  few-flowered  cymes,  fragrant  pink  flowers,  and 
fruit  about  i  inch  in  diameter.  It  is  distributed  from  Pennsylvania  to 
Tennessee  and  Florida. 

M.  coronaria,  American  .Crab-apple. — This  is  a  small,  bushy  tree  with 
thorny,  crooked  branches,  ovate  or  triangular-ovate,  sometimes  three-lobed, 
leaves,  large  flowers,  with  a  persistent  calyx,  and  fruit  that  is  i  to  i3^  inches 
in  diameter,  somewhat  flattened  endwise,  greenish-yellow,  waxy,  fragrant,  and 


38o 


BOTANY   OF   CROP   PLANTS 


Fig.  159, — Leaves  of  Mains  species.  A  and  B,  western  crab  (M.  ioensis); 
C,  flowering  crab  (M.  floribunda);  D,  narrow-leaf  crab  (M.  angustif olia) ;  E, 
Soulard  crab  (M.  soulardi);  F,  common  apple  (Wealthy)  (M.  sylvestris);  G, 
American  crab  (M.  coronaria);  H,  Siberian  crab  (M.  baccata).     X  }-i. 


POMACES  381 

rich  in  malic  acid.  It  grows  wild  in  Ontario  and  North  Atlantic  States,  west 
to  Kansas  and  Missouri. 

M.  ioensis,  Western  or  Prairie  States  Crab-apple. — It  is  a  small  tree  with 
large  leaves,  firm  in  texture  and  of  various  shapes,  large  flowers,  and  green 
fruit  with  light-colored  spots.  It  is  native  of  Minnesota,  Wisconsin,  Illi- 
nois, Iowa,  Missouri,  and  Kansas. 

Bechtel's  Double-flowering  Crab  is  probably  a  double-flowered  form  of 
Malus  ioensis. 

M.  soulardii,  Soulard  Crab. — This  is  a  natural  hybrid  between  the  common 
apple  {M.  sylvestris)  and  the  Western  crab-apple  {M.  ioensis) .  It  is  a  small, 
stout  tree,  with  leavci  similar  to  those  of  M.  ioensis,  in  close  clusters  on  short, 
densely  woolly  pedicels;  the  fruit  is  larger  and  of  better  flavor  than  that  of  M. 
icensis.     It  grows  wild  in  the  Mississippi  Valley. 

M.  sylvestris,  Common  Apple. — The  common  apple  is  a  large  tree  with 
twigs  and  under  surface  of  leaves  gray-woolly;  the  flowers  are  in  close  clusters, 
and  on  short  pedicels;  the  fruit  is  very  variable.  There  are  numerous  varieties 
differing  as  to  form,  size,  color,  and  taste  of  fruit.  In  order  to  keep  the  va- 
rieties true  to  type,  propagation  is  vegetative  rather  than  sexual. 

The  common  apple  is  considered  to  be  a  native  of  western  Asia  and  south- 
eastern Europe.  In  eastern  United  States,  it  occasionally  escapes  from  cul- 
tivation. It  is  grown  commercially  in  all  parts  of  the  United  States  except 
in  Florida,  the  regions  bordering  the  Gulf  of  Mexico,  and  warmer  portions  of 
the  Southwest.  The  leading  apple-growing  section  of  this  country  is  from 
Nova  Scotia  south  and  west  to  Illinois  and  Missouri. 

The  Classification  of  Apples  ( Malus  sylvestris) . — There  have 
been  a  number  of  systems  of  classifying  cultivated  varieties 
of  apples.  A  brief  sketch  of  the  most  important  of  these  is 
given  in'  the  American  Horticultural  Manual  Part  II, 
Systematic  Pomology.  The  principal  classifications  men- 
tioned in  the  above  work  are  those  of  Johann  Jonston,  Ger- 
many 1668,  Manger,  Germany  1780,  Dr.  Diel,  Germany 
1792,  Diel-Cochnahl,  Germany  1855,  Diel-Lucas,  Germany 
1856,  John  A.  Warder,  America  1867,  John  J.  Thomas, 
America  1849,  Robert  Hogg,  England  1876. 

The  system  of  Dr.  Diel  of  Germany,  was  the  first  to  be 
widely  adopted  in  Mo  or  with  modifications.  He  divided  the 
varieties  into  seven  classes,  and  these  into  orders.  These 
classes  are  as  follows:  Ribbed  apples,  Rose  apples,  Ram- 


382 


BOTANY   OP   CROP   PLANTS 


hours,  Reinettes,  Stripelings,  Pointlings,  and  Flat  apples. 
Beach  gives  the  following  groups  of  varieties:  Fall  Pippin, 
Rhode  Island  Greening,  Winesap,  Fameuse,  Alexander  or 
Aport,  Wealthy,  Duchess  of  Oldenburg,  Northern  Spy, 
Blue  Pearmain,  and  Rails-Genet. 

Composition. — According  to  the  determinations  of  Al- 
wood  and  Davidson,  the  average  amount  of  juice  recovered 
from  summer  apples  by  grinding  and  pressing  is  53.2  per 
cent. ;  from  winter  fruit  53.92  per  cent.  Crab-apples  show  an 
average  juice  content  of  57.31  per  cent.  The  average  water 
content  of  the  whole  apple  varies  from  80  to  86  per  cent,  of  its 
total  weight.  It  is  not  possible,  of  course,  to  remove  all  the 
juice  from  apples  by  ordinary  pressing,  and  furthermore,  the 
amount  of  juice  recovered  depends  upon  the  grinding  and 
pressing  methods.  The  above  workers  chemically  analyzed 
the  juice  and  pomace  of  many  varieties.  The  percentage 
composition  of  the  juice  is  shown  in  the  following  table: 


Specific 
gravity 

Total 
solids 

Total 
sugar 

Invert 
sugar 

Cane 
sugar 

Acids  as 
H2SO4 

Tannin 

Summer  varieties 
Autumn  varieties 
Winter  varieties. . 
Crab-apples 

1.049 
I -054 
1.056 
1.062 

12.33 
13   76 
14.29 
15.69 

9-53 
10.66 

11-43 
II. 71 

5. 85 
6.93 
7.04 
8.08 

3-So 
3-53 
4.16 
3.45 

0.33 
0.36 
0.41 
0.50 

0.040 
0.069 
0.050 
0.122 

For  vinegar-making,  a  high  sugar  content  is  desirable.  A 
common  notion  is  that  acid  or  "tartar"  apples  are  better  for 
vinegar-making  than  those  low  in  acid.  The  amount  of  acetic 
acid  in  a  vinegar,  which  is  the  important  test  of  its  quahty, 
is  dependent  upon  the  amount  of  sugar  in  the  juice  (cider) 
and  not  upon  the  acid.  The  sour  taste  of  apples  is  due  to  the 
maUc  acid  present.     So-called  "sweet  apples"  do  not  neces- 


POMACES  383 

sarily  contain  more  sugar  than  "sour  apples,"  but  they  do 
contain  less  acid,  hence  their  "sweetness." 

Cider  and  Vinegar.— Cider  is  the  juice  or  wine  of  apples. 
In  the  transformation  of  cider  to  vinegar,  two  fermentation 
processes  take  place,  in  the  following  order:  (i)  alcoholic 
fermentation,  and  (2)  acetic  acid  fermentation.  When  cider 
"begins  to  work,"  it  is  an  indication  that  the  first  fermenta- 
tion process  is  going  on.  The  sugar  of  the  apple  juice  is  being 
converted  into  alcohol  and  carbon  dioxide.  The  escaping 
of  this  gas  from  the  fermenting  cider  causes  a  "frothing." 
The  process  of  alcoholic  fermentation  is  produced  by  a  micro- 
scopic organism,  the  yeast  plant.  When  the  evolution  of 
carbon  dioxide  gas  has  ceased  and  the  alcohol  is  at  its  maxi- 
mum, the  cider  is  spoken  of  as  hard  cider.  The  second  step 
in  vinegar-making  is  the  conversion  of  the  alcohol  of  the  hard 
cider  into  acetic  acid.  This  change  is  brought  about  by  a 
bacterium,  the  acetic  acid  germ.  The  characteristic  prop- 
erties of  vinegar  are  due  to  acetic  acid. 

Dried  Apples. — The  output  of  dried  apples  in  the  United 
States  in  1909  was  44,000,000  pounds.  Many  housewives 
dry  their  apples  in  the  sun.  When  apples  are  dried  on  a 
large  scale,  they  are  peeled,  cored,  and  sometimes  sliced  by 
machinery.  The  fruit  is  then  dipped  for  a  few  minutes  in  a 
weak  salt  solution,  which  tends  to  prevent  discoloration.  It  is 
then  placed  in  trays  and  taken  to  the  drying  machine.  It  is 
the  practice  in  some  manufacturing  plants  to  subject  the 
apples,  before  drying,  to  sulphur  fumes  for  a  short  time. 
These  fumes  bleach  the  apples  slightly,  and  also  kill  any  or- 
ganisms that  may  be  present.  The  most  common  drying 
method  is  to  pass  hot  air  under  high  pressure  over  the  fruit. 
After  removal  from  the  drying  machine,  the  apples  are  al- 
lowed to  sweat  for  several  days  either  in  the  open  air  or  in 
well-ventilated  chambers.     They  are  then  ready  for  packing. 


384  BOTANY  OF  CROP  PLANTS 

Production  of  Apples  in  the  United  States.^ — In  191 5  there 
were  produced  230,010,000  bushels  of  apples  in  this  country, 
at  an  average  farm  price  per  bushel  of  74.6  cents.  The  ten 
leading  States  in  the  order  of  their  production  were  New  York, 
Missouri,  Ohio,  Pennsylvania,  Illinqis,  Virginia,  Kentucky, 
Indiana,  Iowa  and  Michigan. 

PYRUS  (Pear) 
The  characters  of  this  genus  are  very  similar  to  those  of 
Malus.     The  pears  are  trees  or  shrubs  with  simple  leaves, 
and  large  flowers  in  terminal  cymes,  resembling  those  of  the 


Fig.   160. — A  group  of  stone  cells  and  surrounding  parenchyma  cells  from  the 
flesh  of  pear  (Pyrus  communis).     Highly  magnified. 


apple;  the  styles  are  usually  free  to  the  base.  The  fruit  is 
a  pome,  varying  in  shape,  with  five  carpels,  two  seeds  in  each 
cavity,  and  an  abundance  of  grit  cells  in  the  flesh  (Fig.  160). 

The  two  most  common  species  of  Pyrus  are  Pyrus  communis, 
the  common  pear,  and  Pyrus  serotina  culta,  sand,  Japanese, 
or  Chinese  pear. 

In  the  common  pear,  the  teeth  on  the  leaves  are  obtuse,  the 
flowers  appear  with  the  leaves,  and  the  calyx  is  persistent, 
while  in  the  Japanese  or  Chinese  pear,  the  teeth  on  the  leaves 
are  sharp-pointed  or  bristle-like,  the  flowers  appear  before 
the  leaves,  and  the  calyx  is  deciduous. 


POMACES  385 

PYRUS  COMMUNIS  (Common  Pear) 

Stem. — The  common  pear  is  a  tree  of  upright-growing 
habit.  The  flower  buds  are  mixed  and  terminal,  as  in  most 
apples.  Paddock  and  Whipple  have  shown  that,  in  Colorado 
at  least,  the  Anjou  pear  may  produce  blossom  buds  on  one- 
•year-old  spurs;  that  Bartletts  may  form  bloom  on  the  end  of 
the  last  year's  growth;  that  Anjou,  Bartlett,  Duchess,  and 
Kieffer  varieties  produce  bloom  in  axillary  buds  on  the  last 
year's  growth,  and  that  a  number  of  varieties,  as  Anjou, 
Bartlett,  Duchess  and  Sheldon,  are  annual  bearers.  There 
are  usually  from  six  to  nine  flowers  in  a  bud.  The  ''spurs'' 
are  similar  in  appearance  and  development  to  those  of  the 
apple. 

Leaves  and  Flowers.— The  leaves  are  ovate,  elliptic,  and 
finely  toothed.  The  flowers  are  in  simple  terminal  cymes; 
the  pedicels  are  2  to  3  inches  long,  and  appear  with  the  leaves; 
the  petals  are  five  in  number,  rounded,  short-clawed,  and 
usually  white;  the  sepals  are  persistent;  the  styles  are  distinct 
to  the  base. 

Fruit.— The  fruit  varies  in  shape,  usually  tapering  to  the 
base;  the  flesh  is  with  grit  cells  (Fig.  160)  (groups  of  stone  cells 
imbedded  in  parenchyma) . 

Geographical.— The  common  pear  is  probably  a  native  of  southern  Europe 
and  Asia.  In  many  localities,  it  has  escaped  from  cultivation.  There  are 
numerous  cultivated  varieties.  The  pear  thrives  best  in  the  northern  half  of 
the  United  States. 

PYRUS  SEROTINA  CULTA  (Sand,  Japanese,  or  Chinese  Pear) 

This  is  a  strong-growing  tree  with  broad-ovate,  long- 
pointed  leaves  that  are  very  sharply  toothed.  The  large 
flowers  appear  before  the  leaves.  The  fruit  is  hard  and 
russet-like,  keeps  well,  and  has  a  deciduous  calyx. 

The  tree  is  a  native  of  Chma.  Chmese  Sand,  Madame  von 
25 


386  BOTANY  OF  CROP  PLANTS 

Siebold,  Mikado,  and  Japanese  Sand  are  a  few  of  the  varieties 
growniin;the  United  States.  It  is  also  often  used  to  hybrid- 
ize with  ourjcommon  pear,  the  Kieffer  variety  being  the 
best-known  on^  resulting  from  such  a  cross. 

Self -sterility  in  Pears. — The  work  of  Fletcher  has  pointed 
out  the  reasons  for  the  barrenness  of  many  pear  orchards. 
Much  of  this  is  due  to  self-sterility,  that  is,  the  inabihty  of 
the  pollen  of  a  variety  to  fertihze  the  ovules  in  the  pistils  of 
that  variety.  It  has  been  frequently  observed  in  many 
portions  of  the  country  that  when  a  certain  variety  of  pear,  as 
well  as  other  fruits,  was  planted  thickly,  there  was  often  pro- 
nounced seK-sterility.  This  is  particularly  true,  it  seems,  of 
Bartlett  and  Kieffer  pears.  Fletcher  obtained  the  following 
average  results,  under  Virginia  conditions,  in  self-fertilizing 
Bartlett,  and  in  crossing  with  a  number  of  varieties  (in  the 
table,  the  last  mentioned  variety  of  a  cross  furnished  the 
pollen) : 

Pollinations  Av.   number   of     Av.    weight    of 

blossoms  set  mature  fruit, 

ounces 

Bartiett  X  Bartlett i  in  513  2 .00 

Bartlett  X  Kieflfer i  in    10  3.00 

Bartlett  X  Anjou i  in      7  3-75 

Bartlett  X  Lawrence i  in      9  3 .  50 

Bartlett  X  Duchess i  in    10  3 .  50 

The  following  table  shows  similar  relations  in  the  case  of 
Kieffer  pears: 

Pollinations  Av.    number   of 

blossoms  set 

Kieffer  X  Kieffer i  in  253 

Kieffer  X  Bartlett i  in  5 

Kieffer  X  Le  Conte i  in  7 

Kieffer  X  Lawrence i  in  6 

Kieffer  X  Duchess i  in  5 

Kieffer  X  Anjou i  in  4 

Kieffer  X  Clairgeau i  in  3 

Kieffer  X  Garber i  in  7 


POMACES  .387 

From  these  experiments,  Fletcher  recommends  (under 
Virginia  conditions,  at  least)  that  Anjou,  Lawrence,  Duchess 
and  Kieffer  are  desirable  varieties  to  plant  with  Bartlett, 
and  that  Bartlett,  Le  Conte,  Garber,  Lawrence,  Duchess, 
Anjou,  and  Clairgeau  are  desirable  varieties  to  plant  with 
the  Kieffer. 

It  is  not  probable  that  the  same  degree  of  self-sterility 
for  a  given  variety  will  prevail  under  different  climatic  and 
soil  conditions.  Furthermore,  it  must  be  held  in  mind  that 
no  immediate  effect  of  strange  pollen  need  be  expected  in  the 
resulting  fruit. 

Dwarf  Pears. — The  pear  is  the  most  common  tree  grown 
in  a  dwarf  form  in  the  United  States.  The  usual  method 
of  dwarfing  pears  is  to  graft  them  on  quince  roots,  which  are 
very  slow-growing. 

In  a  graft,  the  two  plants  retain  their  individuality  to  a 
large  degree.  However,  there  are  numerous  instances  cited 
of  the  influence  of  the  stock  upon  the  scion,  or  scion  upon  the 
stock. ^  When  pears  are  grafted  on  the  more  slowly  growing 
roots  of  the  quince,  the  stock  in  this  case  retards  the  growth 
of  the  pear,  and  dwarfing  results.  The  common  quince 
used  in  Angers  and  the  varieties  ordinarily  dwarfed  are 
Angouleme,  Bartlett,  Anjou,  and  Louise  Bonne.  Dwarfing 
appears  to  improve  the  quaHty  of  the  fruit. 

^  If  the  common  apple  is  grafted  on  the  wild  crab,  the  fruit  of  the  scion 
growth  is  more  sour  than  usual.  Late  varieties  of  apple  may  mature  earlier 
when  grafted  on  early  stock.  The  influence  of  the  scion  upon  the  stock  is 
well  shown  in  the  case  of  grafting  the  morning  glory,  an  annual,  upon  the 
sweet  potato,  a  perennial.  In  this  case,  the  tuberous  roots  develop  much 
earlier  than  usual.  A  most  interesting  illustration  is  the  development,  in 
Abutilon,  of  leaves  with  white  spots  (albescent  leaves)  on  a  green-leaved  scion 
when  grown  as  a  graft  upon  an  albescent  stock. 


388  BOTANY   OF   CROP  PLANTS 

CYDONIA  (Quince) 

The  genus  has  much  the  same  characters  as  Malus  and 
Pyrus,  except  that  each  of  the  five  carpels  has  several  seeds, 
covered  with  a  mucilaginous  pulp,  and  the  large  flowers  are 
in  small  clusters  or  sometimes  single  at  the  tips  of  branches. 

There  are  several  species  of  Cydonia,  the  most  common 
being  C.  ohlonga  (edible  quince). 

CYDONIA  OBLONGA  (Common  Quince) 

Stem. — The  common  quince  is  a  small  tree  seldom  over  15 
feet  high,  or  a  shrub,  with  rather  crooked,  slender  branches. 
The  shoots  that  come  from  axillary  buds  and  those  that  come 
from  terminal  buds  may  give  rise  to  flower-bearing  shoots, 
but  it  is  usually  the  case  that  the  largest  fruit  comes  on 
branches  arising  from  axillary  buds  on  the  last  half  of  the 
annual  growth.  The  flowers  are  not  from  fruit  buds  formed 
in  the  autumn ;  after  a  woody  shoot  has  grown  several  inches, 
a  flower  is  produced  which  terminates  the  ■  season's  growth 
of  that  shoot. 

Leaves. — The  leaves  are  alternate,  with  blades  2  to  3 
inches  long,  oval,  somewhat  heart-shaped  or  rounded  at  the 
base,  acute  at  the  apex,  green  above  and  soft-hairy  beneath, 
and  with  petioles  about  >^  inch  long. 

Flowers.' — As  a  rule,  the  flowers  are  solitary;  the  petals 
are  white  or  light  pink;  the  stamens  are  numerous;  there  are 
five  carpels  with  several  ovules  in  each  cavity. 

Fruit.- — The  fruit  may  be  apple-  or  pear-shaped,  hard, 
woolly  when  young,  becoming  smooth  with  age;  the  flesh  is 
free  of  grit  cells;  the  skin  is  yellow  at  maturity;  each  of  the 
five  cells  of  the  ovary  contains  several  seeds  which  have  a 
mucilaginous  coating. 

Varieties. — Bailey    gives    five   varieties    of    the    species. 


POMACES  389 

Cydonia  vulgaris:  Lusitanica,  maliformis,    pyriformis    mar- 
morata,  and  pyramidalis. 

Uses. — Quinces  are  not  usually  eaten  raw  but  made  into 
marmalades,  or  canned.     The  juice  is  sometimes  employed 
to  flavor  manufactured  fruit  products. 
References 

Alwood,  William  B.,  and  Davidson,  R.  J.:  The  Chemical  Compositdon  of 

Apples  and  Cider.     U.  S.  Dept.  Agr.  Bur.  Chem.  Bull.  88:  7-18,  1904. 
Beach,  S.  A.,  Booth,  N.  O.,  and  Taylor,  O.  M.:  The  Apples  of  New  York. 

22d  Ann.  Rept.  N.  Y.  Agr.  Exp.  Sta.,  vol.  i:  1-409;  vol.  2:  1-360,  1903. 
Bigelow,  W.  D.,  Gore,  H.  C,  and  Howard,  B.  J. :  Studies  on  Apples.     U.  S. 

Dept.  Agr.  Bur.  Chem.  Bull.  94:  i-ioo,  1905. 
Black,  Caroline  A. :  The  Nature  of  the  Inflorescence  and  Fruit  of  Pyrus 

malus.     Mem.  N.  Y.  Bot.  Gardens,  6:  519-547,  1916. 
Bradford,  F.  C.  :  The  Pollination  of  the  Pomaceous  Fruits.     II.  Fruit-bud 

Development  of  the  Apple.     Ore.  Agr.  Exp.  Sta.  Bull.  129:  1-16,  1915. 
•  Brooks,  Chas.  :  The  Fruit  Spot  of  Apples.     Bull.  Torrey  Bot.  Club,  35 :  423- 

456,  1908  (includes  notes  on  structure  of  fruit). 
BuDD,  J.  L.,  and  Hansen,  N.  E.:  American  Horticultural  Manual.     Part  II, 

Systematic  Pomology.     John  Wiley  &  Sons,  1911. 
Butler,  O.  :  On  the  Cause  of  Alternate  Bearing  in  the  Apple.     Bull.  Torrey 

Bot.  Club,  44:  85-95,  1917- 
Chittenden,  F.  J. :  Pollination  in  Orchards.     III.  Self-f ruitfulness  and  Self- 
sterility  in  Apples.     Jour.  Hort.  Soc,  39:  615-628,  1914. 
Decaisne,  Joseph:  Memoire  sur  la  famille  des  Pomacees.     Nouvelles  Ar- 
chives du  Museum,  X,  pp.  113-192  (Paris),  1875. 

Le  jardin  fruitier  du  museum,  un  iconographie  de  touts  les  especes  et 
varietes  d'arbres  fruitiers  cultives  dans   cet  etablissement.     Firmin 
Didot  Freres. 
Drinkard,  a.  W.:  Fruit-bud  Formation  and  Development.     Rept.  Vir.  Agr. 

Exp.  Sta.,  1909-1910:  159-205,  191 1. 
EwERT,  K.:  Die  Parthenokarpie  der  Obstbaume.     Ber.  Deut.  Bot.  Gesell., 

24:  414-416,  1906. 
Die  Parthenocarpie  der  Obstbaume.     Ber.  Bot.  Ges.,  26:  414-416,  1906. 
Fletcher,  S.  W.:  Pollination  of  Bartlett  and  Kieffer  Pears.     Reprint  from 

Ann.  Rept.  Va.  Agr.  Exp.  Sta.,  1909:  212-232. 
Pollination  of  Bartlett  and  Kieffer  pears.     Ann.  Rept.  Va.  Agr.  Exp.  Sta., 

1909  and  1910:  213-224,  1911. 
GoFF,  E.  S. :  The  Origin  and  Early  Development  of  the  Flowers  in  the  Cherry, 

Plum,  Apple  and  Pear.     i6th  Ann.  Rept.  Wis.  Agr.  Exp.  Sta.,  290-303, 

1899. 


390  BOTANY  OF  CROP  PLANTS 

Investigations  of  Flower  Buds.     17th  Ann.  Rept.  Wis.  Agr.  Exp.  Sta.,  266- 

285,  1900. 
Investigation  of  Flower  Buds.     i8th  Ann.  Rept.  Wis.  Agr.  Exp.  Sta.  304- 

316,  1901. 
Origin  and  Development  of  the  Apple  Blossom.     Am.  Gard.,  22:  330  and 
346-347,  1901. 
Gardner,  V.  R.,  Wagness,  J.  R.,  and  Yeager,  A.  F.:  Pruning  Investiga- 
tions.    Oregon  Agri.  Exp.  Sta.  Bull.  139:  1-88,  1916. 
GouRLEY,  J.  H. :  Studies  in  Fruit  Bud  Formation.    N.  H  Agr.  Exp.  Sta.,  Tech. 

Bull.  9:  1-79,  1915. 
Hardy,  J.  A.,  and  A.  F.:  Traite  de  la  taille  des  arbres  fruitiers,  ed.  12,  123, 

Paris. 
Hedrick,  y.  P.:  Dwarf  Apples.     N.  Y.  Agr.  Exp.  Sta.  Bull.  406:  341-368, 

1915-. 
Kraus,  E.  J. :  The  Pollination  of  the  Pomaceous  Fruits.     I.  Gross  Morphology 
of  the  Apple.     Ore.  Agr.  Exp.  Sta.  Res.  BuU.  I,  pt.  I:  1-12,  1913. 
The  Study  of  Fruit  Buds  in  Oregon.     Ore.  Agr.  Exp.  Sta.  Bull.  130:  12-21, 

1915- 
Variation  of  Internal  Structure  of  Apple  Varieties.     Ore.  Agr.  Exp.  Sta. 

Bull.  135:  3-42,  1916. 
Kraus,  E.  J.,  and  Ralston,  G.  S.:  The  Pollination  of  the  Pomaceous  Fruits. 

III.  Gross  Vascular  Anatomy  of  the  Apple.     Ore.  Agr.  Exp.  Sta.  Bull. 

138:  4-12,  1916. 
Lewis,  C.  I.,  and  Vincent,  C.  C.:  Pollination  of  the  Apple.     Ore.  Agr.  Exp. 

Sta.  Bull.  104:  1-40,  1909. 
McAlpine,  D.:  The  Fibro-vascular  System  of  the  Apple  and  its  Function. 

Proc.  Linn.  Soc,  N.  S.  Wales,  36:  613-625,  1911. 
The  Fibro-vascular  System  of  the  Quince  Fruit  Compared  with  that  of 

the  Apple  and  Pear.     Proc.  Linn.  N.  S.  Wales,  37:  689-697,  1912. 
Paddock,  W.  and  Whipple,  O.  B.:  Fruit  Growing  in  Arid  Rfegions.     Mac- 

Millan  Co.,  1910. 
Pickett,  B.  S.:  Factors  Influencing  the  Formation  of  Fruit  Buds  in  Apple 

Trees.     Trans.  Mass.  Hort.  Soc,  pt.  I:  57-72,  1913- 
Sandsten,  E.  p.:  Some  Conditions  Which  Influence  the  Germination  and 

Fertility  of  Pollen.     Wis.  Agr.  Exp.  Sta.  Research  Bull.  4:  149-172, 

1909. 
Shaw,  J.  K.:  The  Technical  Description  of  Apples.     Mass.  Agr.  Exp.  Sta. 

Bull.  159:  73-90,  1914- 
Waite,  W.  B.;  The  Pollination  of  Pear  Flowers.     U.  S.  Dept.  Agr.  Div.  Veg. 

Path,  and  Phys.  Bull.  5:  i-iio,  1894. 
West,  G.  H.:  The  Pollination  of  Apples  and  Pears.     Trans.  Kans.  State 

Hort.  Soc,  32:  38-50,  191 2. 


CHAPTER  XXVIII 


DRUPACE^  (Plum  Fanuly) 

Habit,  Stems.^ — Representatives  of  the  plum  family  are 
trees  or  shrubs.  The  bark  exudes  a  gum,  and  the  leaves, 
bark,  and  seeds  are  bitter,  and  contain  prussic  acid.  Many- 
cases  of  poisoning  have  been 
recorded  from  eating  the  seeds 
of  peach  and  bitter  almond,  and 
it  is  also  known  that  stock  is 
poisoned  from  eating  the  leaves 
of  wild  cherries.  The  glucoside, 
amygdalin,  acted  on  by  emulsin, 
an  enzyme,  in  the  presence  of 
water  is  changed  to  prussic  acid, 
grape  sugar,  and  benzaldehyde. 
Prussic  acid  is  deadly  poisonous 
even  in  small  amounts. 

are 

com- 

The 

often 


Leaves. — The      leaves 
alternate,    petioled    and 
monly    finely     toothed, 
teeth    and    petiole    are 
glandular  (Fig.  i6i) ;  the  stipules 
are  early  deciduous. 

Flowers. — The  perfect,  regu- 
lar flowers  (Fig.  162)  are 
solitary  (apricot),  or  in  racemes  (wild  black  cherry,  etc.), 
umbels  (sweet  cherry,  etc.),  or  corymbs  (perfumed  cherry). 
The  calyx  is  free  from  the  ovary,  five-lobed,  bell-shaped  or 
391 


Pig.  161. — Leaf  of  peach 
(Amygdalus  persica).  The  base 
of  the  leaf  considerably  enlarged, 
in  B. 


392 


BOTANY   OF   CROP   PLANTS 


tubular  and  with  its  lobes  imbricated  in  the  bud;  the  corolla 
has  five  distinct  petals;  there  are  numerous  stamens.     In  a 


em 


Fig.  162. — Floral  diagram  of  Prunus. 


^nm  oj  receplacle 


Fig.  163. — Sour  cherry   (Prunus  cerasus).     Median  lengthwise   section  of 
flower. 


longitudinal  section  (Fig.  163)  of  the  drupaceous,  flower,  it  is 
seen  that  the.  ovary  is  placed  down  within  a  cup  commonly 


DRUPACE^ 


393 


called  the  "calyx  tube."  If  it  is  a  calyx  tube,  then  petals 
and  stamens  are  inserted  upon  it.  It  is  very  probable  that 
this  tube  is  receptacle  and  that  calyx,  corolla  and  stamens  are 
mounted  thereupon.  There  is  one  pistil,  situated  at  the 
bottom  of  the  hollow  receptacle;  the  ovary  is  one-celled  and 
two-ovuled ;  the  style  is .  single  and  terminal  and  bears  a 
small,  head-shaped  stigma. 


^P'^te^f 


otyledons 


fcotmaons 
of  emhnjo 

cahx 


Fig.   164. — Median  lengthwise  section  of  young  cherry  frui 


Fruit.^ — The  fruit  is  a  drupe  (Fig.  164),  that  i 
a  single  seed  surrounded  by  a  stony  endocarp,  fleshy  meso- 
carp,  and  an  outer  skin  or  exocarp  (epicarp).     However,  if 
one  examines  the  young  ovary  of  a  Frunus  flower  he  wiU  find 


394  •  BOTANY  OF  CROP  PLANTS 

two  ovules;  one  of  them  aborts,  the  other  develops  into  a 
seed.  The  endosperm  is  absent,  or  present  only  in  a  small 
amount.     The  cotyledons  are  fleshy. 

The  only  genus  of  any  importance  is  Prunus.  It  has  the 
characteristics  of  the  family. 

PRUNUS 

This  genus  includes  the  plum,  cherry,  ahnond,  peach  and 
apricot.  These  main  groups  may  be  distinguished  by  the 
following  key : 

Key  to  Main  Groups  of  Genus  Prunus 

Stone  smooth. 

Flowers  clustered;  fruit  glabrous. 
Fruit  large,  usually  grooved,  covered  with  a  bloom;  stalk  short;  stone 
usually  compressed,  longer  than  broad;  leaves  convolute  in  the  bud 
(Fig.  loi),  Plums. 
Fruit  small,  usually  not  grooved,  not  covered  with  a  bloom;  stalk  long; 
stone  usually  globular;  leaves   conduplicate   in  the  bud  (Fig.  loi), 
Cherries. 
Flowers  solitary  or  in  two's;  fruit  velvety  at  first.  Apricots. 
Stone  pitted  or  furrowed. 

Flesh  soft,  thick,  juicy,  Peaches. 
Flesh  hard,  thin,  dry.  Almonds. 

The  genus  has  about  90  species,  nearly  all  of  which  occur 
north  of  the  equator;  they  are  widely  distributed  in  both 
eastern  and  western  hemispheres.  Most  species  are  con- 
fined to  the  temperate  zone.  The  evergreen  cherries  include 
a  group  found  in  the  tropics  and  sub  tropics. 

PLUMS 

Stems. — The  plums  are  shrubs  or  small  trees.  The 
different  species  vary  considerably  in  bark  and  twig  charac- 
ters. The  bark  of  southern  forms  is  lighter  in  color  than 
that  of  those  growing  in  the  north.     Plums  have  a  tendency 


DRUPACE^ 


395 


to  produce  spurs  (Fig.  165).     Flower  buds  are,  as  a  rule,  on 

these  spurs,  one  spur  bearing  from  2  to  20  buds.     The  spur 

may  terminate  in  a  leaf  bud.     However,  in  most  plums,  true 

terminal  buds  are  seldom  formed.     In 

such  cases,  if  the  last  lateral  bud  is  a 

branch  bud,  this  continues  the  growth 

of  the  branch  in  a  straight  line.     The 

Hne  between  the  two  seasons'  growths 

is  not  as  sharp,  in  this  case,  as  when  a 

terminal  bud   develops.      If    the   last 

lateral  bud  is  a  flower  bud,  the  twig 

usually  dies  back  to  the  lateral  branch 

developed  from  the  last  branch  bud. 

In  all  plums,  the  flower  buds  are  lateral. 

Flower  buds  usually  stand  out  at  an 

angle  of  about  30°,  while  leaf  buds  are 

more  appressed  to  the  stem. 

Leaves. — The  leaves  of  plums  vary  a 
great  deal  in  size,  form,  color,  surface, 
thickness,  and  margin.  In  some  species, 
the  serrations  are  tipped  by  glandular 
prickles.  Stipules  are  present.  The 
leaves  are  convolute  in  the  bud  (Fig. 

lOl). 

Inflorescence. — The  flower  ^^  buds  of 
the  plum,  unHke  those  of  the  apple  and 
pear,  bear  only  flowers.  They  may 
break  open  before,  simultaneously  with, 
or  after  the  leaf  buds.  The  flowers  are 
in  fascicled  umbels.  The  number  of 
flowers  in  the  bud  varies  from  one  to  five,  two  and  three 
being  the  most  common  numbers. 

Flowers. — The  receptacle  forms  a  hollow  cup  (Fig.  163). 


Fig.  165. — Twig  of 
Domestica  plum 
(Prunus  domestica) . 
{After  Paddock  and 
Whipple.) 


396  BOTANY   OF   CROP   PLANTS 

On  its  edge,  are  arranged  five  sepals,  five  petals,  and  fifteen 
to  twenty  stamens.  There  is  a  single  pistil  bearing  one  style 
and  one  stigma.  The  pistil  is  at  the  bottom  of  the  recep- 
tacle. There  are  two  ovules  in  the  young  ovary;  one  of  them 
aborts  during  maturation  of  the  fruit. 

"Fertilization. — Many  of  the  plums  are  practically  self- 
sterile.  The  native  plums  exhibit  the  greatest  self-steriHty ; 
this  is  due  to  the  impotency  of  the  pollen  when  used  on  the 
stigma  of  the  same  flower.  Japanese  and  domestic  plums  are 
less  self-sterile  than  native  species.  In  some  cases,  not  only 
are  pistils  developed  that  are  so  weak  as  to  fail  even  if  polli- 
nated, but  some  flowers  do  not  form  pistils.  Again,  pistils  and 
stamens  of  the  same  flower  often  mature  at  different  times. 
Usually,  the  pistils  mature  first.  Rarely,  the  opposite  is 
the  case.  Hence  it  is  seen  that  cross-fertiHzation  is  very  nec- 
essary in  plum  orchards,  but  not  only  cross-fertilization  be- 
tween different  trees  of  the  same  variety  but  between  dif- 
ferent varieties.  It  is  reported  by  Hendrickson  that  French 
and  sugar  prunes  in  California  set  a  very  Hght  crop  unless  a 
large  number  of  bees  are  present  in  the  orchard  at  the  time 
of  blooming.  They  appear  to  be  self-sterile  to  some  extent. 
Imperial  prune  trees  that  were  enclosed  in  a  tent  from  which 
all  insects  were  excluded  set  no  fruit.  It  seems  that,  with  the 
Imperial  prune,  fruit  is  not  set  unless  pollen  is  brought  from 
other  trees.  It  is  distinctly  self-sterile.  All  Prunus  species 
are  insect-poUinated  for  the  most  part. 

Fruit. — ^After  fertilization,  the  receptacle,  with  its  attached 
sepals,  petals,  and  stamens,  is  cut  off  by  a  circular  abscission 
layer  near  its  base  (Fig.  164).  The  ovary  wall  increases  in 
thickness  to  form  the  following  fruit  parts  (Fig.  164):  (i) 
skin,  exocarp;  (2)  flesh,  mesocarp;  and  (3)  hard  stony  layer 
about  the  seed,  endocarp.  The  style  and  stigma  do  not  per- 
sist in  the  fruit.     The  seed  is  within  the  endocarp.     Hence 


DRUPACEiE  397 

the  stone  ("pit")  of  the  plum  consists  of  hardened  endocarp, 
seed  coat,  and  embryo.     The  stone  is  compressed. 

Classification  of  Plums.- — For  a  complete  description  of  the 
species  of  plums  in  American  plum  culture,  see  "The  Plums 
of  New  York";  Hedrick,  Report  of  the  N.  Y.  Agr.  Exp.  Sta., 
vol.  3,  pt.  II,  1911;  and  Wight,  W.  F.,  "Native  American 
Species  of  Prunus,"  Bull.  179,  B.  P.  I.,  1915. 

Key  to  Principal  Species  of  Pltjms  * 

Flowers  in  clusters  of  one  or  two  (three  in  P.  Iriflora),  Old  World  Plums. 
Shoots  and  pedicels  pubescent. 

Fruits  large,  more  than   i   inch  in  diameter,  variable  in  shape,  often 

compressed;  tree  large;  stamens  about  30,  P.  domestica. 
Fruits  small,  less  than  i  inch  in  diameter,  uniformly  oval  or  ovoid; 
tree  small,  compact;  stamens  about  25,  P.  insUitia. 
Shoots  glabrous  or  soon  becoming  so,  pedicels  glabrous. 
Flowers  mostly  single,  P.  cerasifera. 
Flowers  in  threes,  P.  Iriflora. 
Flowers  in  clusters  of  three  or  more,  rarely  two,  American   Plums. 
Leaf  serrations  glandless,  acute;  calyx  lobes  entire,  glabrous  on  the  outer, 

pubescent  on  the  inner  surface,  not  glandular,  P.  americana. 
Leaf  serrations  glandular  (at  least  when  they  first  unfold),  rounded  or  ob- 
tuse; calyx  lobes  glandular  (except  in  P.  angustifolia). 
Leaves  broad,  mostly  oblong-ovate  or  obovate,  the  margin  often  doubly 
serrate;  flowers  2  to   2.5   centimeters  broad;   calyx   with  a  reddish 
tinge,  at  least  when  old,  the  lobes  glandular  serrate,  P.  riigra. 
Leaves  narrow,  ovate,  ovate-lanceolate,  the  margin  rarely  doubly  serrate; 
flowers  8  to  15  millimeters  broad;  calyx  rarely  reddish,  the  lobes  entire, 
either  glandular  or  glandless. 
Leaves  thick,  slightly  lustrous  on  upper  surface;  veins  conspicuous  below; 

margin  coarsely  and  irregularly  serrate,  P.  horlulana. 
Leaves  usually  thin,  lustrous  on  upper  surface,  veins  not  conspicuous 
below,  margin  finely  and  evenly  serrate. 
Leaves  usually  6  to  10  centimeters  long;  calyx  lobes  glandular,  P. 

munsoniana. 
Leaves  2  to  6  centimeters  long;  calyx  lobes  glandless,  P.  angustifolia. 

*  Adapted  from  The  Plums  of  New  York  by  Hedrick. 


398  BOTANY   OF   CROP  PLANTS 

DISCUSSION  OF  SPECIES 

Prunus  domestica. — This  is  a  vigorous-growing  tree 
which  may  reach  a  height  of  30  or  40  feet.  The  leaves  are 
ovate  or  obovate,  elliptical  or  oblong-eUiptical;  the  upper 
surface  is  smooth,  the  lower  often  j&nely  hairy,  the  margins 
coarsely  toothed,  and  the  teeth  often  glandular.  The  flowers 
usually  appear  after  the  leaves,  sometimes  with  them.  The 
fruit  is  generally  globular,  the  skin  varies  in  color,  the  flesh 
is  yellowish,  and  the  stone  free  or  clinging. 

This  is  the  best  known  and  most  widely  distributed  species 
of  plums.  It  has  been  cultivated  for  2,000  years,  originally 
coming  from  about  the  Caucasus  Mountains.  The  first 
colonists  brought  varieties  of  this  species  to  North  America. 
There  are  now  over  950  varieties  of  Domestic  plums  grown 
in  this  country.  These  have  been  divided  into  a  number  of 
groups,  largely  based  upon  fruit  characteristics.  These 
groups  are  as  follows: 

1 .  Green  Gages  (Reine  Claude) . — These  are  low  trees  with 
dark  bark  which  cracks  deeply,  with  leaves  doubly  toothed, 
fruit  relatively  small,  round,  mostly  green  or  golden,  and  of 
excellent  quahty.  The  stone  is  either  free  or  clinging. 
Important  varieties  are  Reine  Claude,  Bavay,  Spaulding, 
Yellow  Gage,  Washington,  etc. 

2.  Prunes. — A  prune  is  any  plum  that  can  be  cured  without 
removing  the  pit.  All  plums  with  a  large  percentage  of  sugar 
make  good  prunes.  The  fruit  is  large,  oval,  usually  com- 
pressed, blue  or  purple,  and  with  a  firm,  greenish,  yellow,  or 
golden  flesh,  and  free  stone.  Prunes  are  raised  on  the  Pacific 
Coast.  The  industry  there  has  become  a  large  one.  Im- 
portant varieties  are  Italian,  German,  Agen,  Tragedy,  Ten- 
nant,  Sugar,  Giant,  Pacific,  and  Ungarish. 

Preparation  of  Prunes. — In  the  preparation  of  prunes,  the 


DRUPACEiE  399 

plums  are  first  cleaned,  and  their  skins  ruptured  to  permit  of 
more  rapid  drying.  Usually,  they  are  dipped  into  boiling 
water  or  hot  lye,  which  not  only  cleans  but  also  cracks  the 
skin.  They  are  then  dried  in  the  open  sun,  or  in  drying 
sheds  where  artificial  heat  may  be  utiHzed.  After  drying, 
the  prunes  are  allowed  to  "sweat"  for  two  or  three  weeks. 
They  are  then  graded  and  "glossed"  or  finished  by  heating 
in  steam  or  immersing  in  salted  boiling  water,  glycerine  or 
fruit  juice.  This  gives  the  surface  of  the  prunes  a  shiny 
appearance,  and  also  steriHzes  the  exterior. 

3.  Peridrigon  Plums. — This  is  a  prune  plum  grown  only 
in  France. 

4.  Yellow  Egg  Plums. — The  fruit  of  these  is  large,  in  fact 
the  largest  of  plums,  long-oval,  and  has  a  yellow  or  purple 
skin,  and  yellow  flesh.  Well-known  varieties  are  Yellow 
Egg,  Red  Magnum  Bonum,  Golden  Drop,  and  Monroe. 

5.  Imperatrice  Plums. — These  are  medium-sized,  dark 
blue  plums,  with  thick  skin,  firm  flesh,  and  clinging  stones. 
Such  varieties  as  Ickwor^h,  Arch  Duke,  Monarch,  Shipper, 
Arctic,  etc.,  belong  to  this  group. 

6.  Lombard  Plums. — This  group  includes  the  reddish  or 
mottled  varieties  of  Domestic  plums.  Lombard,  Bradshaw, 
Victoria,  Pond,  and  Duane  are  well-known  varieties. 

Primus  insititia. — This  is  a  small  tree  not  over  25  feet  high 
with  small  ovate  or  obovate,  finely  toothed  leaves  which  are 
usually  glandular;  both  surfaces  of  the  leaves  are  sHghtly 
hairy.  The  flowers  are  usually  in  lateral,  umbellate  clusters. 
The  fruit  is  globular  or  oval,  small,  usually  bluish  black  or 
golden  yellow,  and  has  yellow  flesh,  and  a  chnging  or  free 
stone. 

Varieties  of  this  species  are  hardy  and  thrifty.  The  species 
has  been  in  cultivation  over  2,000  years,  but  in  all  that  time 
has  shown  but  little  variation.     Insititia  plums  rank  second 


400  BOTANY  OF  CROP  PLANTS 

to  Domesticas.  The  species  grows  wild  from  the  Mediterra- 
nean northward  into  Norway,  Sweden  and  Russia.  Insititia 
plums  fall  into  four  groups  as  follows: 

1.  Damsons. — These  are  spicy  plums,  mostly  sour,  and 
much  desired  for  preserving. 

2.  Bullaces. — This  group  contains  a  few  varieties  differing 
but  little  from  the  preceding  group,  except  as  to  fruit  shape. 
The  Bullaces  are  spherical. 

3.  Mirabelles. — These  are  round,  yellowish  or  golden  plums 
with  a  free  stone  and  resemble  much  the  green  gages  as  to 
quaHty. 

4.  St.  Juliens. — This  is  a  name  applied  to  a  group  of  plums 
resembling  the  Damsons.  They  were  formerly  used  in  this 
country  as  stocks. 

Primus  cerasifera. — These  are  the  cherry  or  Myrobalan  plums.  They  are 
hardy,  thrifty  varieties,  free  from  disease,  readily  adaptable  and  most  suitable 
for  hybridizing.  The  trees  are  small,  bloom  profusely,  and  bear  a  small, 
round,  cherry-like  plum  from  3^  to  i  inch  in  diameter.  They  are  adapted 
to  ornamental  usage.  They  are  also  used  as  stocks  upon  which  to  bud 
other  plums.  \ 

Pninus  triflora. — These  are  the  Japanese  plums;  they  are  not  cultivated 
in  many  parts  of  the  world.  They  are  native  of  China.  It  is  a  highly  adapt- 
able group,  vigorous,  productive,  early-bearing,  and  disease-free.  Varieties 
are,  for  the  most  part,  cling  stones. 

Prunus  americana. — This  is  our  most  important  native  plum.  It  grows 
wild  from  New  Mexico  to  Manitoba,  and  eastward  to  the  Atlantic  Coast. 
Not  being  able  to  raise  European  plums  in  the  Mississippi  VaUey,  Americans 
domesticated  the  native  American  plum.  Varieties  of  this  species  are  hardy. 
The  American  plum  tree  is  usually  small,  with  rough,  shaggy  bark.  The 
fruit  is  reddish  or  yellowish.  Altogether,  there  are  about  260  varieties  of 
the  americana.  Waugh  finds  that  they  often  bear  defective  pistils  or 
stamens,  or  that  they  are  often  protandrous  or  protogynous.  From  his 
observations,  he  recommends  some  provisions  for  cross-fertilization  when 
planting  americanas. 

Prunus  hortulana. — This  species  includes  a  number  of  plums  well  suited 
for  jelly,  preserves,  and  spicing.  They  are  very  free  of  suckers.  Important 
varieties  are  American,  Golden,  Juicy,  Ruby,  Waugh,  and  Gonzales.  The 
Hortulanas  are  adapted  to  the  Southern  StaJtes. 


DRUPACE^ 


401 


Prunus  nigra. — This  is  the  most  northern  of  American  plums.  It  is  well 
adapted  to  the  States  along  the  Canadian  border. 

Prunus  munsoniana. — This  is  the  plum  most  grown  in  the  South.  The 
varieties  are  mostly  cling  stones.  Of  all  plums,  these  are  most  in  need  of 
cross-pollination.  A  few  of  the  chief  varieties  are  Robinson,  Newman,  Wild 
Goose,  Arkansas,  and  Downing. 

Pninus  angustifolia. — The  Chickasaw  plum  is  a  small  tree,  6  to  10  feet 
high,  sometimes  shrubby.  The  fruit  is  small,  almost  globular,  flesh  yellow, 
and  of  good  quality.  It  ranges  from  Delaware  to  Louisiana  and  westward 
to  Arkansas  and  Texas.     Its  varieties  do  well  in  the  Southern  States. 

The  two  subspecies,  watsoni  and  varians,  have  varieties  of  some  horti- 
cultural value,  such  as  Purple  Panhandle,  African,  Clark,  Emerson,  etc. 

CHERRIES 


corolla 
I       .ca\\j. 


Description.^ — The  cher- 
ries resemble  plums  in 
many  respects.  The  bark 
of  the  cherry  separates  in 
rings.  The  flower  buds  are 
usually  found  on  short 
spurs  (Fig.  166).  In  some 
sour  cherries,  however, 
axillary  flower  buds  occur 
on  long,  strong  shoots. 
These  buds  produce  fruit 
the  following  spring.  Since 
the  lateral  buds  in  such 
shoots  are  flower-bearing, 
no  lateral  branches  are  pro- 
duced, and  the  result  is  a 
long,  naked  branch.  On  the 
spurs,  the  flower  buds  are 
axillary  and  a  branch  bud 
terminates  the  short  shoot. 

The  flower  buds  bear  only  flowers  and  no  leaves  (except  very 
rudimentary  ones  which  persist  but  for  a  short  time).     There 
26 


)^rowih 


Fig.  166.- 


-Spur  of  sour  cherry  (Prunus 
cerasus) . 


402  BOTANY  OP  CROP  PLANTS 

are  from  two  to  five  blossoms,  usually  two,  in  each  bud.  The 
flowers  are  in  umbels,  as  a  rule.  The  flowers  and  fruit  of 
cherries  are,  morphologically,  similar  to  those  of  plums. 

The  leading  commercial  varieties  of  cherries  grown  in 
CaKfornia  have  been  shown  to  be  self-sterile.  It  is  altogether 
possible  that  sterility  in  cherries  is  widely  spread. 

Groups  of  Cherries. — According  to  Bailey  the  principal 
cultivated  cherries  are  from  two  species,  Prunus  avium,  the 
sweet  cherries,  and  Prunus  cerasus,  the  sour  cherries. 

PRUNTJS  AVIUM  (Sweet  Cherry) 

Description. — The  sweet  cherry  is  a  tall  tree,  strong-grow- 
ing, long-lived,  and  frequently  attains  a  diameter  of  i  foot 
or  more.  The  bark  is  gray-brown,  the  outer  layer  often 
being  roughened;  lenticels  are  inconspicuous.  The  leaves 
are  thick,  oval,  ovate  or  obovate,  4  to  12  centimeters  long, 
abruptly  short-acuminate,  irregularly  and  coarsely  toothed, 
or  doubly  so,  green  and  smooth  above,  lighter  beneath, 
slightly  hairy  on  the  veins,  more  or  less  drooping,  and  with 
long  slender  petioles.  Flowers  appear  with  the  leaves,  in 
lateral,  sessile  umbels;  the  flower  pedicels  are  3  to  6  centi- 
meters long;  the  petals  are  white,  and  the  stamens  35  or  36. 
Self-steriHty  has  been  reported  in  the  sweet  cherry  orchards 
of  the  Northwest.  The  fruit  is  variously  colored,  spherical 
to  heart-shaped,  with  flesh  soft  or  hard,  usually  sweet,  and 
with  the  skin  adherent  to  the  flesh. 

Geographical. — The  species  is  a  native  of  Europe.  It  has  been  cultivated 
in  this  country  for  many  years,  and  in  some  places  has  escaped  from 
cultivation. 

Groups  of  Sweet  Cherries. — The  sweet  cherries  include 
four  general  groups: 

I.  Mazzards: — The  fruit  is  small,  and  varies  in  shape  and 
color.     Mahaleb  and  mazzard  stocks  are  the  two  common 


DRUPACE^ 


403 


sorts  upon  which  sweet  cherries  are  grafted,  the  results  being 
somewhat  better  when  grown  on  mazzard  stock.  Sour  cher- 
ries are  also  propagated  on  mazzard  stock. 

2.  Hearts  (Geans). — The  fruit  is  heart- 
shaped  and  has  a  soft  flesh.  Tartarian, 
Black  Eagle,  etc.,  are  varieties  in  this  group. 

3.  Bigarreaus. — The  fruit  is  heart-shaped, 
light  or  dark  in  color,  and  with  hard  flesh. 
Common  black  varieties  are  Windsor  and 
Schmidt,  common  light  ones,  Yellow  Spanish 
and  Napoleon. 

4.  Dukes. — Dukes  resemble  the  Hearts  in 
shape  and  color,  but  have  a  juice  somewhat 
acid.  Dukes  are  often  classed  with  the  sour 
cherries,  but  Bailey  would  class  them  with 
the  sweet  cherries  on  account  of  the  habit  of 
growth  of  the  trees,  and  the  flower  and  leaf 
characters.  Hedrick  considers  Duke  cherries 
as  hybrids  between  Prunus  avium  and  P. 
cerasus.  They  resemble  sweets  more  than 
sour.  Dukes  commonly  produce  sterile  seed. 
There  are  both  dark-  and  light-colored  sorts. 
Reine  Hortense  and  May  Duke  belong  here. 


PRUNUS  CERASUS  (Sour  Cherry) 

Description. — Sour  cherry  trees  are  smaller 
than  those  of  sweet  cherries.  They  "sucker  ^ 
readily  from  the  root.  The  bark  is  gray- 
brown  and  quite  smooth;  lenticels  are  con- 
spicuous. The  leaves  are  thick,  ovate  or 
ovate-lanceolate,  abruptly  acute  or  acuminate  at  the  tip, 
variously  toothed,  becoming  smooth  on  both  surfaces,  usually 
erect,  and  with  short,  strong  petioles.    Flowers  appear  before 


Fig.  167. — Twig 
of  sweet  cherry 
(Prunus  avium). 
(After  Paddock 
and  Whipple.) 


404 


BOTANY   OF   CROP  PLANTS 


or  with  the  leaves  in  small  umbels  from  lateral  buds;  the 
pedicels  are  about  24  centimeters  long;  and  the  stamens  are 
about  30  in  number.     The  fruit  is  globular,  always  red,  with 

soft  flesh  and  skin  that  usually  separates 

readily  from  pulp. 

Geographical. — The  species  is  a  native  of 
Europe  and  an  occasional  escape  from  cultiva- 
tion in  this  country. 

Groups  of  Sour  Cherries.^The  sour 
cherries  include  two  general  groups: 

1.  Amarelles. — These  cherries  are  pale 
red  in  color,  have  colorless  juice,  and  are 
generally  somewhat  flattened  on  the 
ends.  They  have  less  acid  than  dark- 
colored  cherries.  Montmorency  and 
Early  Richmond  are  the  most  common 
Amarelles, 

2.  Morellos  or  Griottes. — These  are 
cherries  with  dark  red  fruit  and  dark 
juice,  and  they  vary  from  spherical  to 
heart-shape.  Common  varieties  are 
Ostheim,  Olivet,  Louis  Phihppe,  and 
the  Morello. 


Fig.  168. — Twig  of 
sour  cherry  (Prunus 
cerasus).  {After  Pad- 
dock and  Whipple.) 


Other  Species  of  Cherries. — The  species  of  cher- 
ries native  to  America  are  of  little  horticultural 
importance.  Chief  of  these  are  P.  pennsylvanica, 
P.  emarginata,  P.  pumila,  P.  cuneata,  and  P. 
besseyi.  P.  pennsylvanica  is  sometimes  used  as  a 
stock  on  which  to  bud  the  sour  cherry. 

Prunus  mahaleh,  a  native  of  Europe  and  Asia,  is  very  extensively  used  in 
this  country  as  a  stock  for  all  sweet  and  sour  cherries.  It  is  an  excellent 
dwarfing  stock. 

Uses. — Both  sour  and  sweet  cherries  are  used  as  a  dessert 
fruit,  and  in  the  making  of  pies.     The  bulk  of  the  cherries 


DRUPACEiE  405 

grown  for  canning  purposes  are  sour  red  sorts,  and  are  pro- 
duced in  New  York,  Michigan,  Wisconsin,  and  California. 
Maraschinos  are  sweet  cherries,  most  of  which  are  imported 
from  Italy  and  Spain.  A  Californian  variety,  Napoleon,  is 
also  used  to  some  extent  for  this  purpose.  Recent  investiga- 
tions point  to  the  conclusion  that  a  number  of  commercial 
products  may  be  obtained  from  cherry  pits  and  cherry  juice, 
two  by-products  of  the  cherry  industry.  The  fixed  oil 
expressed  from  the  fresh  kernels  is  much  like  almond  oil,  and 
can  be  utihzed  in  similar  ways.  Also,  the  volatile  oil  is  quite 
similar  to  bitter-almond  oil,  and  can  be  used  in  the  same  way. 
The  pressed  cake,  that  which  remains  after  the  oils  are  re- 
moved, may  be  ground  into  a  meal  and  used  as  a  feeding 
stuff.  The  waste  cherry  juice  can  be  changed  into  syrup, 
jelly  and  alcohol. 

APRICOTS 

Stems. — The  common  apricot  varieties  belong  to  the 
species  Prunus  armeniaca.  The  trees  are  small,  round- 
topped,  and  resemble  the  peach  tree.  As  in  the  plums,  true 
terminal  buds  are  seldom  formed.  Lateral  branch  buds  and 
flower  buds  are  found  together  in  the  axils  of  leaves  (Fig. 
169).  Except  for  a  few  rudimentary  leaves,  the  fruit  buds 
bear  only  flowers.  Normally,  there  is  but  one  flower  (some- 
times two)  in  a  bud;  they  appear  before  the  leaves.  The 
flower  buds,  which  are  lateral,  occur  singly  at  nodes;  often 
three  buds  are  developed  in  the  axil  of  a  leaf,  the  central 
one  being  a  branch  bud,  while  the  two  laterals  are  flower 
buds.  However,  not  all  branch  buds  on  a  twig  are  accom- 
panied by  flower  buds.  The  vigor  of  the  tree  and  twigs,  and 
pruning  methods  will  determine  the  position  of  the  latter,  to 
some  extent.  In  strong-growing  twigs,  the  flower  buds  are 
rather  near  the  tip  of  a  year's  growth;  on  twigs  of  moderate 


4o6 


BOTANY   OF   CROP   PLANTS 


growth,  they  will  be  found  along  the  central  portion  of  the 
twig;  while  on  feeble-growing  branches,  they  usually  occur 
singly,  and  are  quite  evenly  distributed  along  the  entire 

length.  However,  not  all 
the  flower  buds  are  formed 
on  the  long  shoots.  Many 
are  developed  on  ex- 
tremely '  short  spurs,  but 
always  axillary;  usually 
the  flower  buds  are  single 
in  such  short  growths. 

Leaves. — These  are  usu- 
ally ovate,  often  somewhat 
heart-shaped  at  the  base, 
abruptly  short-acuminate, 
smooth  above,  sHghtly 
hairy  ^beneath,  finely 
toothed,  on  glandular 
petioles,  and  convolute  in 
vernation. 

Inflorescence  and 
Flowers. — The  flowers  are 
soHtary  or  in  pairs,  pink- 
ish, sessile  or  nearly  so. 
Morphologically,  the 
flowers  are  similar  to  those 
of  plum,  cherry  and  other 
Prunus  spp. 

Fruit. — This  is  much 
like  a  peach  in  color  and  shape;  the  skin  is  velvety  at  first, 
but  becomes  smooth  at  maturity;  the  flesh  is  always 
yellow.  The  stone  (endocarp  and  seed)  is  flat,  smooth,  and 
grooved  on  one  edge.     In  the  maturing  of  the  fruit,  the 


Fig.  169. — Twigs  of-  apricot  (Prunus 
armeniaca).  (After  Paddock  and 
Whipple.) 


DRUPACE^ 


407 


parts  of  the  flower  are  cut  off  by  a  basal  ring  of  growth,  as 
described  in  the  plums. 

Distribution. — The  species  is  considered  to  be  a 
native  of  southern  Asia.  It  is  now  cultivated  in 
most  temperate  climates.  In  the  United  States,  the 
practice  is  to  graft  apricots  on  to  the  roots  of  plum  or 
peach. 

Other  Species. — There  are  several  other  species 
of  apricots  besides  P.  armeniaca,  but  none  of  them 
bear  fruit  of  marketable  size.  They  are  generally 
planted  as  ornamentals.  Among  such  are  P.  sibirica, 
the  Siberian  apricot,  P.  dasycarpa,  the  purple  or  black 
apricot,  and  P.  mume,  the  Japanese  apricot. 

Uses. — Apricots  are  prized  as  a  table 
fruit,  both  in  the  fresh  and  the  dried  con- 
dition. They  are  usually  pitted  before 
they  are  dried,  but  may  be  dried  with  the 
skins  off  or  on.  "Sulphuring"  may  pre- 
cede the  drying  process  proper.  Almond 
oil  is  derived  from  the  seeds. 

PEACHES 

The  common  varieties  of  peaches  come 
from  one  species — Prunus  persica.  Some 
writers  place  the  peach  in  a  separate 
genus,  Amygdalus  persica.  The  latter  is 
the  name  given  to  the  peach  by  Linnaeus. 

Stems. — The  tree  is  low,  seldom  over 
25  feet  in  height,  broad- topped,  and  with 
a  scaly,  dark  brown  bark.  Young  twigs 
are  glossy  green.  The  flower  buds  of  the 
peach  are  simple,  containing  only  flowers,  or  flowers  and  a 
few  rudimentary  leaves;  each  bud  has  one,  sometimes  two, 
flowers.     The  flower  buds  are  borne  singly  or  in  pairs  with 


Fig.  170. — Twigs 
of  pe!0.ch  (Prunus 
persica).  (After Pad- 
dock and  Whipple.) 


408  BOTANY  OF  CROP  PLANTS 

a  branch  bud  (Fig.  170).  In  this  respect,  they  are  similar 
to  the  apricot. 

Leaves. — These  are  conduplicate  (Fig.  10 1)  in  the  bud, 
elHptic  to  lanceolate  or  oblong,  and  taper  toward  either  end; 
they  are  finely  and  sharply  toothed,  and  on  stout  petioles. 

Inflorescence  and  Flowers.— The  flowers  are  normally 
solitary  in  the  axils  of  leaves  and  appear  before  the  leaves; 
they  are  large,  pink,  fragrant,  and  showy. 

Fruit. — The  fruit  is  subglobular,  grooved  slightly  on  one 
side,  has  velvety  skin,  and  hard  flesh  which  may  be  free 
(freestones)  or  adherent  (clingstones)  to  the  stone.  The 
stone  is  compressed,  pointed,  and  pitted.  The  seed  is  of 
the  shape  of  an  almond,  aromatic,  and  sHghtly  bitter. 

Geographical. — The  peach  is  a  native  of  Asia,  probably  China.  It  was  in- 
troduced into  Europe  at  a  very  early  date,  coming  by  way  of  Persia.  This 
fact  accounts  for  the  specific  name,  persica,  and  common  name,  peach. 
The  tree  is  now  cultivated  in  temperate  regions.  Occasionally  it  is  escaped 
from  cultivation,  especially  throughout  our  Northern  and  Middle  States. 

Types  of  Peaches.^ — The  first  system  of  classification  of 
peaches  was  worked  out  by  Onderdonk,  of  Texas.  He 
divides  the  varieties  of  peaches  into  five  classes  or  races, 
based  primarily  upon  the  country  in  which  they  originated, 
hence  upon  their  range  of  adaptabihty. 

1.  Peen-to  Race. — The  stone  is  almost  spherical  (Fig. 
171,  C,  D),  somewhat  compressed  at  the  end,  and  with  small 
and  round  corrugations;  the  fruit  (of  original  peen-to)  is  much 
flattened;  the  skin  is  white,  blotched  with  red,  and  flesh 
white;  the  stone  is  free  or  cling.  It  is  adapted  to  subtropical 
regions.     Varieties:  Angel,  Clara,  Hall,  Waldo. 

2.  South  China  Race  ("Honey"  Group). — The  stone  is 
oval  (Fig.  171,  B),  and  its  corrugations  slight;  the  fruit  is 
slightly  flattened,  with  a  peculiar  long,  conical  apex  more 
or  less  recurved,  small,  oval,  and  has  a  very  deep  suture  at 


DRUPACE^ 


409 


the  stem  end;  the  flesh  is  juicy,  firm,  generally  white;  the 
stone  is  free  or  cling.  It  is  adapted  to  subtropical  condi- 
tions.    Varieties:  Climax,  Imperial,  Pallas,  Taber. 

3.  Spanish  Race. — The  stone  is  large,  oval,  nearly  flat 
(Fig.  171,  A),  its  apex  prominent,  and  corrugations  small; 
the  fruit  is  large,  yellow,  or  yellow  streaked  with  red.  It  is 
adapted  to  southern  conditions.  Varieties:  Cabler,  Druid, 
Onderdonk,  Texas. 


Fig.  171 . — Fruit  of  the  races  of  peaches.  A ,  Spanish  Race;  B,  South  Chin- 
ese Race;  C,  Peen-to  Race;  D,  stone  of  Peen-to  Race;  E,  Persian  Race;  F, 
stone  of  Persian  Race;  G,  North  Chinese  Race.  {After  Price,  Texas  Agr.  Exp. 
Sta.) 


4.  North  China  Race  ("Chinese  Clings"). — The  stone  (Fig. 
171,  G)  is  globular,  thick,  its  corrugations  not  at  all  promi- 
nent, chng,  semi-chng  or  free;  the  fruit  is  large,  almost  glob- 
ular, and  its  flesh  is  fine-grained  and  juicy.  It  has  a  wide 
range  of  adaptability.  Varieties:  Belle,  Lee  Ray,  Superb. 
Elberta  and  several  other  varieties  are  considered  crosses 
between  the  North  China  and  Persian  races. 


4IO  BOTANY  OF  CROP  PLANTS 

5.  Persian  Race. — The  seed  is  globular,  with  corrugations 
prominent  toward  the  apex  (Fig.  171,  E,  F) ;  the  fruit  is  much 
hke  the  preceding.  The  common  varieties  of  peaches  grown 
in  northern  orchards  belong  to  this  race.  Varieties:  Crothers, 
Foster,  Late  Crawford,  Reeves,  Salway,  Walker. 

In  addition  to  the  above,  the  Nectarine  should  be  added 
as  a  variety  of  peach.  It  differs  from  the  common  peach  in 
that  its  fruit  is  smaller,  the  skin  is  smoother,  and  the  leaves 
are  commonly"  more  prominently  toothed.  There  are  both 
freestone  and  clingstone  nectarines.  It  is  known  that 
nectarines  appear  on  peach  trees  and  peaches  on  nectarine 
trees.  Such  fruits  that  thus  appear  are  evidently  "bud 
variants." 

Uses,  and  Production  of  Peaches  in  the  United  States. — 
The  fruit  is  used  largely  as  a  dessert,  both  fresh,  dried  and 
canned.  Peaches  are  usually  pitted  before  they  are  dried. 
The  seeds  of  the  peach,  as  well  as  those  of  almond,  apricot 
and  plums,  contain  both  fixed  and  volatile  oils,  which  are  of 
commercial  value. 

There  are  peach  interests  of  commercial  importance  in  a 
large  proportion  of  the  States.  The  total  output  of  peaches 
for  the  country  in  191 5  was  64,218,000  bushels,  which  were 
sold  at  an  average  farm  price  of  81.1  cents.  CaHfornia  led 
in  production,  with  9,768,000  bushels.  The  other  nine  lead- 
ing States,  in  the  order  of  their  output,  were  Arkansas, 
Georgia,  Texas,  Missouri,  Alabama,  Kansas,  Tennessee, 
Oklahoma  and  Ohio. 

ALMONDS 

Description. — The  common  almond  is  Prunus  amygdalus 
(Amygdalus\ommunis).  The  tree  is  much  Hke  the  peach  in 
shape  and 'size.  The  flower  buds  are  axillary  along  with 
branch  buds,  as  in  the  peach  and  apricot.     The  leaves  are 


DRUPACE^  411 

lanceolate,  firm,  shining,  and  finely  toothed.  The  flowers  are 
normally  solitary  and  appear  before  the  leaves.  They  are 
large,  pink,  and  showy.  Many  varieties  are  sterile  without 
cross-fertiKzation.  The  drupe  is  much  compressed.  The 
mesocarp  (portion  corresponding  to  the  flesh  of  peach  or 
plum)  is  leathery  and  tough  and  separates  readily  at  maturity 
from  the  stone  (endocarp  and  seed).  The  "unshelled" 
almond  of  commerce  consists  of  the  thin,  pitted,  light-colored 
endocarp,  within  which  is  the  seed  or  "kernel." 

The  common  almond  is  a  native  of  Asia. 

Types  of  Almonds.^ — The  two  general  types  or  races  of 
common  almonds  are  the  hitter  and  the  sweet.  The  difference 
is  in  the  composition  and  taste  of  the  kernel.  The  sweet  or 
edible  almonds  consist  of  two  groups:  Hard-shell  and  soft- 
shell.     The  latter  are  of  the  greater  economic  importance. 

In  addition  to  the  common  almonds,  Prunus  amygdalus, 
there  are  a  number  of  dwarf  forms  which  are  grown  mostly 
as  ornamentals. 

Uses. — Almonds  are  grown  for  the  nuts  which  are  used 
directly  as  a  food.  Almond  oil  finds  use  in  the  manufacture 
of  flavoring  extracts.  The  seeds  are  also  a  source  of  prussic 
acid. 

Almond  Oil. — Most  of  the  so-called  oil  of  almonds  is 
derived  from  the  seeds  of  the  apricot;  ahnond  and  peach 
seeds  also  furnish  a  considerable  quantity.  The  oils  from 
these  three  sources  are  very  nearly  the  same.  In  the  process 
of  extracting  almond  oil,  the  seeds  are  ground,  subjected  to 
great  hydraulic  pressure  to  remove  the  undesirable  fatty 
oil,  and  the  residue  ground  again,  fermented,  and  distilled 
with  steam.  The  distillate  is  almond  oil  and  hydrocyanic 
acid.  This  latter,  deadly  poisonous  substance  is  removed  by 
treating  the  mixture  with  Hme  and  copperas. 


412  BOTANY  OF  CROP  PLANTS 

References 

Bailey,  L.  H:  Fourth  Report  on  Japanese  Plums.     Cornell  Exp.  Sta.  Bull. 

175:  131-160,  1899. 
Bailey,  L.  H.,  and  Powell,  G.  H.:  Cherries.     Cornell  Agr.  Exp.  Sta.  Bull. 

98:  471-500,  1895. 
Earle,  F.  S.:  Japanese  Plums.     Ala.  Agr.  Exp.  Sta.  Bull.  85:  423-448,  1897. 
Gardner,  V.  R.:  A  Preliminary   Report  on  the  Pollination  of  the  Sweet 

Cherry.     Ore.  Agr.  Exp.  Sta.  Bull.  116:  1-40,  1913. 
Goethe,  R.:  Uber  die  Klassification  der  Pfirsichsorten.     Gartenflora,  55: 

169-182,  1907. 
Gould,  H.  P.:  Growing  Peaches:  Varieties  and  Classification.     U.  S.  Dept. 

Agr.  Farmers'  Bull.  633:  1-18,  1914. 
Hedrick,  V.  P.:  The  Cherries  of  New  York.     2 2d  Ann.  Rept.  N.  Y.  Agr. 

Exp.  Sta.,  vol.  2,  part  2:  1-37 1,  1915- 
The  Plums  of  New  York.     i8th  Ann.  Rept.  N.  Y.  Agr.  Exp.  Sta.,  vol.  3, 

part  2:  1-616,  1911. 
The  Blooming  Season  of  Hardy  Fruits.     N.  Y.  Agr.  Exp.  Sta.  Bull.  407: 

367-391,  1915. 
Hendrickson,   a.   H.:  The    Common   Honey  Bee  as  an  Agent  in  Prune 

Pollination.     Calif.  Agr.  Exp.  Sta.  Bull.  174:  127-132,  1916. 
Hume,  Harold  H.  :  The  Peen-to  Peach  Group.     Fla.  Agr.  Exp.  Sta.  Bull.  62 : 

505-519,  1902. 
Onderdonk,  Gilbert:  Report  of  the  Commissioner  of  Agr.,  1887,  pp.  648- 

650.     Containing  the  Original  Classification  of  the  American  Varieties 

of  Peaches. 
Powell,  G.  Harold:  The  Chinese  Cling  Group  of  Peaches.     Del.  Agr.  Exp. 

Sta.  Bull.  54:  1-32,  1902. 
Price,  R.  H.:  The  Peach.     Tex.  Agr.. Exp.  Sta.  Bull.  39:  803-848,  1896. 
Quaintance,  a.  L.:  The  Development  of  the  Fruit  Buds  of  the  Peach.     Ga. 

Exp.  Sta.  Rept.  13:  349-351,  1900- 
Rabak,  Frank:  Peach,  Apricot,  and  Prune  Kernels  as  By-products  of  the 

Fruit  Industry  of  the  United  States.     U.  S.  Dept.,  Bur.  Plant  Indus.  Bull. 

133:  1-34,  1908. 
The  Utilization  of  Cherry  By-products.     U.  S.  Dept.,  Bur.  Plant  Indus. 

Bull.  350:  1-24,  1916. 
Reimer,  F.  C:  The  Honey  Peach  Group.     Fla.  Agr.  Exp.  Sta.  Bull.  73=  135" 

153,  1904. 
Wight,  W.  F.:  Systematic  Botany  of  the  Plum  as  Related  to  the  Breeding. 

of  New  Varieties.     Ann.  Rept.  Am.  Breeders'  Assn.,  8:  488-497,  191 2. 
The  Varieties  of  Plums  Derived  from  Native  American  species.    U.  S.  Dept. 

Agr.  Bull.  172:  1-44,  191 5. 
Native  American  Species  of  Pr«»M^.     U.S.  Dept.  Agr.  Bull.  179:  1-75,1915. 


CHAPTER  XXIX 
LEGUMmOS^  (Pea  Family) 

The  pea  family  is  one  of  wide  geographical  distribution, 
occurring  both  in  temperate  and  warm  climates.  According 
to  Piper  there  are  about  487  genera  and  10,782  species  in 
the  family.  Of  these,  3,846  species  in  103  genera  are 
American. 

''Legume^'  is  a  popular  name  applied  to  members  of  the 
Leguminosae.  Probably  no  family  is  of  greater  agricultural 
importance  than  this  one,  unless  it  is  the  Graminese.  Legu- 
minous plants  are  comparatively  rich  in  protein;  this  applies 
to  all  portions  of  the  plant,  and  not  to  seeds  alone.  For  this 
reason  they  help  to  balance  the  food  ration  of  man  and  of 
domestic  animals,  which  is  quite  largely  made  up  of  starchy 
foods,  such  as  are  furnished  by  the  cereal  crops.  Further- 
more, the  fact  that  legumes  are  rich  in  nitrogenous  sub- 
stances makes  them  of  value  as  fertilizer  crops.  Moreover, 
they  leave  a  considerable  quantity  of  vegetation  behind  them 
when  harvested,  and  thus  add  humus  to  the  soil,  which 
improves  both  the  chemical  and  physical  properties  of  the 
soil. 

Root  Tubercles. — The  roots  of  the  legumes  support  the 
growth  of  a  bacterium  {Pseudomonas  radicicola)  which  forms 
upon  them  abnormal  growths  called  nodules  or  tubercles. 
The  tubercles  are  root  colonies  of  the  above  organism,  which 
stimulates  rapid  growth  of  certain  root  cells  and  hence  the 
formation  of  swollen,  gall-Hke  structures.  These  organisms 
have  the  power  of  fixing  free  nitrogen  of  the  air.  That  is, 
free  nitrogen  gas  from  the  soil  air  is  taken  by  the  organism 
413 


414  BOTANY  OF  CROP  PLANTS 

and,  together  with  other  chemical  elements,  made  a  part  of 
its  protein.  It  is  probable  that  the  legume  bacteria,  while 
active  in  the  nodule,  are  throwing  off  continuously  nitroge- 
nous substances  which  are  absorbed  directly  by  the  plant 
upon  which  they  are  growing.  Moreover,  when  the  nodules 
decompose,  their  protein  contents  are  ammonified,  and 
nitrified,  and  finally  there  is  left  in  the  soil,  nitrates  which  are 
available  as  a  source  of  nitrogen  for  green  plants.  Legumes 
are  regularly  employed  as  rotation  crops  with  cereals,  and 
root  crops.  Since  they  are  heavy  soil  feeders,  they  make 
excellent  crops  to  plow  under. 

Habit. — ^Leguminosae  are  either  annual,  biennial  or  peren- 
nial; and  are  either  herbs  (peas,  beans,  alfalfa,  etc.),  shrubs 
{Genista,  dye-weed  or  green-weed),  or  trees  {Rohinia  and 
Gleditsia,  locusts),  and  a  very  few  are  vines  {Vicia  spp., 
vetches). 

Leaves. — These  are  alternate  on  the  stems,  stipulate,  and 
mostly  compound.  They  are  generally  odd-pinnate,  that 
is,  a  leaflet  terminates  the  rachis  of  the  leaf,  as  in  Rohinia 
(locust).  Astragalus  (vetches)  and  Aragallus  (loco) ;  sometimes 
they  are  even-pinnate,  that  is,  terminated  by  a  tendril  or 
bristle,  as  in  Vicia  (vetch)  and  Lathyrus  (wild  and  sweet 
peas) ;  or  they  may  be  trifoliate,  as  in  clovers,  or  digitate,  as 
in  Thermopsis  (buckbean). 

Liflorescence. — The  flowers  are  nearly  always  arranged  in 
racemes  (pea),  sometimes  in  a  head  (clovers),  or  spike-like 
raceme  (alfalfa),  or  spike  (Glycyrrhiza,  licorice). 

Flowers. — These  are  irregular  (Fig.  172);  they  have  a 
butterfly-hke  shape,  and  for  this  reason,  flowers  of  the  pea 
type  are  often  spoken  of  as  "papiHonaceous."  The  calyx 
is  normally  four-  to  five-toothed  or  cleft,  the  teeth  or  lobes 
being  equal  or  unequal.  The  petals  are  usually  five  in 
number,  a  broad  upper  one  (standard,  banner  or  vexillum), 


LEGUMINOS^  415 

two  lateral  ones  {wings  or  alee),  and  two  lower  ones  more  or 
less  united  along  their  ventral  edges  (forming  the  keel  or 
carina)  (Fig.  172);  this  keel  encloses  the  stamens  and  pistils. 
In  the  bud,  the  keel  is  enclosed  by  the  wings,  and  the  wings 
by  the  standard.  Stamens  are  mostly  ten  in  number,  and 
either  all  the  filaments  are  united  {monadelphous) ,  as  in 
Lupinus,  or  nine  are  united  and  one  is  free  (Fig.  188)  (diadel- 
phous),  as  in  clovers  and  alfalfa,  or  rarely  all  stamens  are 
separate    (polydelphous) ,   as   in  Sophora   and   Thermopsis. 


Fig.  172. — Flower  of  Leguminosae.  A,  floral  diagram  of  Vicia  faba;  B, 
sweet  pea""  flower,  dissected,  diagrammatic.  {A  after  Eichler,  B  after  Bergen 
and  Caldwell.) 

The  united  stamens  form  a  tube  enclosing  the  pistil  in 
monadelphous  and  diadelphous  forms.  There  is  a  single 
superior  pistil;  the  ovary  is  usually  one-celled,  sometimes 
two-celled  by  the  intrusion  of  the  sutures,  as  in  some  Astraga- 
lus spp.,  or  occasionally  several-celled  by  cross-partitions; 
there  is  one  style,  and  one  to  many  ovules. 

Fruit. — In  nearly  all  members  of  the  family,  the  fruit  is  a 
legume  or  pod,  that  is,  a  fruit  of  one  carpel  which  opens  along 
two,  both  the  ventral  and  dorsal,  sutures.  The  ventral 
suture  of  the  bean  or  pea  pod,  for  example,  is  the  one  along 
which  the  seeds  are  attached.     In  one  tribe  (Hedysareae) , 


4l6  BOTANY  OF  CROP  PLANTS 

the  fruit  is  a  loment,  that  is,  a  jointed  indehiscent  legume, 
constricted  between  the  seeds.  The  style,  calyx,  and 
withered  stamens  are  often  partly  persistent  in  the  fruit. 

Seeds. — The  seeds  are  usually  without  endosperm;  the 
cotyledons  are  thick  and  full  of  food. 

The  seeds  of  legumes  are  noted  for  their  great  longevity. 
Some  have  been  known  to  retain  their  viability  for  150  to 
250  years.  This  is  correlated  with  their  very  hard,  imper- 
meable seed  coats.  So-called  "hard  seeds"  are  very  com- 
mon in  the  pea  family.  Such  seeds  are  tardy  in  their  ger- 
mination, either  under  laboratory  or  field  conditions.  As  a 
rule,  only  a  portion  of  a  crop  of  seeds  is  hard,  although  in 
some  cases  the  whole  crop  may  be  hard.  It  is  claimed  that  a 
larger  percentage  of  hard  seeds  is  produced  in  dry  chmates 
or  when  ripening  takes  place  under  dry  seasonal  conditions 
than  in  moist  climates  or  moist  seasons.  The  permeabihty 
of  leguminous  seeds  can  be  increased  by  "scarifying," 
that  is,  passing  them  through  a  machine  that  abrases  the 
surfaces.  The  ordinary  alfalfa  huller  is  effective  as  an 
abraser,  as  is  shown  by  the  experiments  of  Harringtjon  who 
found  that  alfalfa  seed,  grown  tinder  a  variety  of  soil  and 
climatic  conditions,  had  about  90  per  cent,  of  hard  seeds  if 
hulled  by  hand  and  only  about  20  per  cent,  if  hulled  by 
machine. 

Key  to  Principal  Genera  of  Leguminos^ 

Plants  with  tendril-bearing  leaves  (Fig.  19). 

Calyx  lobes  leafy;  stipules  large,  rounded  (Fig.  19),  Pisum  (pea). 
Calyx  lobes  not  leafy;  stipules  mostly  small,  pointed. 
Style  slender,  bearded  at  the  tip  (Fig.  173,  A;,  Vicia  (vetch). 
Style  flattened,  bearded  along  the  inner  side   (Fig.  173,  B),  Lathyrus 
(vetchling). 
Plants  without  tendril-bearing  leaves. 
Leaves  palmately  three-foliate  (Fig.  183),  TrifoUum  (clover). 
Leaves  pinnately  three-foliate,  rarely  five-  to  seven-foliate  (Fig.  182).     , 


LEGUMINOSiE  417 

Flowers  small,  many  in  a  cluster. 

Flowers  in  slender,  spike-like  racemes,  Melilolus  (sweet  clover). 
Flowers  in  heads  or  short  spikes,  Medicago  (alfalfa  and  other  medicks). 
Flowers  medium  to  large,  few  in  a  cluster. 
Pods  smooth,  mostly  large. 

Keel  of  corolla  spirally  coiled  (Fig.  176,  A),  Phaseolus  (bean). 
Keel  of  corolla  merely  incurved,  Vigna  (cowpea). 
Pods  hairy,  small,  Soja  (soy  bean). 
Leaves  pinnate,  with  two  pairs  of  leaflets,  Arachis  (peanut). 

PISUM  (Pea) 

Description. — The  plants  are  herbaceous  trailers  or 
climbers  with  hollow  stems.  The  leaves  are  pinnately 
compound,  with  one  to  three  pairs  of  leaflets,  the  terminal 
one,  and  in  some  cases  the  upper  lateral  ones,  modified  as 
tendrils,  which  are  sensitive  and  prehensile;  the  stipules  are 
large  and  leaf-like  (Fig.  19).  The  inflorescence  is  a  few- 
flowered  axillary  raceme.  The 
flowers  are  either  white  or  pur- 
plish, diadelphous,  and  bear  a 
single  pistil  with  the  style 
bearded  on  the  inner  side  (Fig. 
173,  A).  The  pea  is  capable  of 
self-fertilization  although  it 
may  sometimes  be  cross-ferti- 
lized.     The    mature  fruit   is    a       Fig.  173— ^.  style  and  stigma  of 

Vicia;  B,  same  of  Lathryus. 

typical  legume  with  a  number 

of  smooth  or  wrinkled,  usually  green  or  yellow  seeds 
("peas")-  Gregory  studied  the  histology  of  round  and 
wrinkled  peas.  In  round  peas,  including  the  indented  sugar 
peas,  the  central  tissue  in  the  cotyledon  leaves  is  filled  with 
very  large  starch  grains.  In  wrinkled  peas,  on  the  other 
hand,  this  region  of  the  cotyledons  has  starch  grains  which  are 
usually  compound,  the  component  parts  being  about  one-half 
the  size  of  the  grains  in  smooth  peas.  The  seed  coat  is 
27 


4l8  BOTANY   OF   CROP  PLANTS 

thin;  endosperm  is  wanting;  the  stored  food  is  within  the  two 
cotyledons.  The  cotyledons  remain  underground  during 
germination  {hypogean  germination),  as  in  all  cereals.  This 
type  of  germination  is  different  from  that  in  the  bean  and 
squash,  for  example,  in  which  the  two  cotyledons  are  raised 
above  ground,  and  for  a  time  are  food-making  organs. 
This  sort  of  germination  is  called  epigean. 

Types  of  Peas. — There  are  but  two  well-recognized  types 
of  Pisum:  Garden  peas  and  field  peas.  These  are  briefly 
distinguished  as  follows: 

Flowers  white;  seeds  globular,  uniformly  yellowish,  white  or  bluish  green; 
leaf  axils  green,  unpigmented;  comparatively  tender  Pisum  sativum 
(garden  pea). 

Flowers  colored,  usually  purplish,  red  or  lavender;  seeds  angular,  gray- 
brown,  gray-green,  gray-yellow  or  gray  speckled  with  fine  spots  of  various 
colors;  leaf  axils  pigmented;  comparatively  hardy  Pisum  salivuvi  (field 
pea). 

Garden  Peas. — The  common  garden  pea  can  be  divided 
into  two  groups:  Shelling  peas,  and  edible-podded  or  sugar 
peas.  In  the  former,  the  pod  is  lined  on  the  inside  by  a  thin, 
hard  membrane  (endocarp)  which  at  maturity  causes  it  to 
split  open.  In  the  edible-podded  or  sugar  peas,  this  mem- 
brane does  not  become  dry  and  twisted  at  maturity,  and 
the  pods  remain  soft  and  tender. 

Shelling  Peas. — Vilmorin  classifies  the  varieties  of  common 
shelling  peas  into  two  groups:  Round  or  smooth-seeded,  and 
•wrinkled-seeded.  Each  of  these  is  divided  into  (i)  tall  climb- 
ing, (2)  half-dwarf,  and  (3)  dwarf  varieties,  and  each  of  the 
latter  three  groups  into  white-seeded  and  green-seeded  sorts. 
The  sugar  peas  occur  in  both  tall,  half -dwarf,  and  dwarf 
forms. 

Period  of  Maturing. — As  a  general  rule,  the  earliest  sorts 
of  peas  have  smooth,  round  seeds,  while  the  late  sorts  have 


LEGUiMINOS.E 


419 


wrinkled  seeds.  SmouLh-seeded  varieties  are  hardier  than 
wrinkled-seed  varieties.  This  is  not  invariably  the  case, 
however.  Furthermore,  dwarf  and  medium-sized  forms 
are  early,  while  tall  \-arieties  are  late.     Green  garden  peas 


Fig.  174. — Pea  pods  showing  types  and  range  of  variation.  A,  extra  early 
dwarf  wrinkled  pea,  American  Wonder;  B,  medium  early  wrinkled  pea, 
Xutt's  Excelsior;  C,  main  crop  smooth  pea,  Marrowfat.      (After  Corbelt.) 

are  sometimes  classified  as  to  their  time  of  maturing  into 
early,  medium,  and  late  or  main  crop.  First,. of  all,  Alaska, 
and  American  Wonder  are  examples  otearl-'  i-=  ^'>  ^  f^ans, 
Advancer,   and  Pride   of  Market  01   u       an,  'le 

among  late-maturing  crops  are  such  varieties  as  ,  ^one, 
Telegraph  and  White  Marrow  Fat. 


420 


BOTANY  OF  CROP  PLANTS 


Field  or  Canadian  Field  Peas. — These  have  smooth,  hard, 
rather  angular  seeds.  They  are  gray-green,  gray-yellowish, 
or  gray  dotted  with  purple,  blue,  rust  red  or  brownish  spots. 
Garden  peas  are  sometimes  used  as  a  field  crop. 


Fig.  175. — Pea  pods  showing  types  and  range  of  variation.  D,  French  can- 
ning type  smooth  pea,  French  Canner;  E,  large  podded  wrinkled  pea,  Pride  of 
Market;  F,  fleshy  or  edible  podded  pea.  Melting  Sugar.      {Afler  Corbelt.) 


Field  peas  are  successfully  grown  only  in  those  regions  with 
a  cool  gfewing  season,  in  fact,  they  will  withstand  quite 
\^Q^-7  T-  .ci.  "^-Tigh  temperatures  accompanied  by  high 
re  .aic_      to  decidedly  injurious.     Excellent  crops 

are  ^  -        a-t  7,000  to  8,000  feet  in  the  San  Luis  Valley  of 
Colorado.^    They  do  well  on  most  types  of  soil. 


LEGUMINOS^  421 

Peas  and  Mendelism. — Gregor  Mendel's  famous  experiments  in  plant 
hybridization  were  carried  on  with  the  common  garden  pea.  He  discovered 
certain  laws  in  the  behavior  of  his  hybrids,  and  these  are  now  famed  as 
Mendel's  Laws.  He  selected  a  number  of  differentiating  (paired)  characters 
and  observed  their  behavior  when  crossed  with  each  other.  In  the  brief 
summary,  here  of  his  work,  a  number  of  characters  of  the  genus  Pisum  are 
brought  out: 

1.  Round  or  roundish  form  of  seed  is  dominant  over  angular  or  wrinkled 
seed.  That  is,  when  a  plant  bearing  roundish  seeds  is  crossed  with  one  bear- 
ing angular  or  wrinkled  seeds,  the  hybrid  offspring  bears  seeds  all  of  which  are 
roundish. 

2.  Yellow  color  of  cotyledons  is  dominant  over  green  color  of  cotyledons. 

3.  Gray  seed  coats  are  dominant  over  white  seed  coats. 

4.  Inflated  seed  pods  are  dominant  over  pods  constricted  between  the  seeds. 

5.  Green  color  of  unripe  pods  is  dominant  over  yellow  color  of  unripe  pods. 

6.  Distribution  of  flowers  in  leaf  axils  is  dominant  over  their  distribution  on 
the  ends  of  stems. 

7.  Tall  stem  is  dominant  over  short  stem.  j 

Uses. — Peas  in  the  green  state  are  one  of  the  most  common 
vegetables.  They  are  also  canned  in  large  quantities.  Field 
peas  are  being  grown  as  a  companion  crop,  soiling  crop, 
green  manure,  and  as  a  food  for  hogs,  sheep,  horses  and 
cattle.  It  is  the  practice  in  many  places  to  pasture  live 
stock,  particularly  hogs  and  sheep,  on  field  peas. 

PHASEOLUS  (Bean) 

Description. — Representatives  of  this  genus  are  annual  or 
perennial  herbs  or  vines  with  pinnately  three-foliate,  rarely 
one-foliate,  leaves.  The  flowers  occur  in  axillary  racemes; 
they  vary  in  color :  white,  yellow,  red,  or  purple.  The  calyx 
is  five-toothed  or  five-lobed,  the  two  upper  teeth  or  lobes 
being  either  united  or  free.  The  standard  of  the  corolla  is 
often  recurved  or  somewhat  contorted;  the  wings  equal  or 
exceed  the  standard,  while  the  keel  is  characteristically  spirally 
coiled  (Fig.  176,  A).  The  stamens  are  diadelphous  (nine 
and  one).     The  ovary  has  a  style  longitudinally  bearded,  and 


422 


BOTANY  OF  CROP  PLANTS 


numerous  ovules.  Members  of  the  genus  are  quite  regularly 
visited  by  insects.  The  pod  is  linear,  straight  or  curved, 
subterete  or  compressed,   two-valved,   and  tipped  with  a 

persistent  style.  The  seeds 
("beans")  are  large  and 
have  a  prominent,  approx- 
imately central  hilum,  on 
one  side  of  which  is  the 
micropyle,  on  the  other, 
the  raphe.  The  embryo  is 
large  and  occupies  the 
whole  of  the  seed,  i.e., 
endosperm  is  wanting. 
The  hypocotyl  and 
plumule  are  prominent; 
the  two  large  cotyledons 
are  slightly  concave  on 
their  inner  faces.  The 
germination  of  the  bean, 
and  the  bean  seedhng,  are 
common  objects  of  study 
in  general  botanical 
courses. 


Geographical    and    Species. — 

Members  of  the  genus  Phaseolus 
are  tropical  and  warm-country 
plants.  According  to  Britton  and 
Brown,    there    are   close  to   i8o 


Fig.  176. — Common  kidney  bean 
(Phaseolus  vulgaris).  A,  spiral  keel;  B, 
entire  flower.      X  2j^. 


species. 

A  number  of  "beans"  do  not 
fall  within  the  genus  Phaseolus,  for  example,  broad  bean  {Vicia  faba),  soy 
bean  (Soja  max),  velvet  bean  (Mucuna  utilis),  asparagus  or  dolichos  bean 
{Vigna  sesquipedalis) ,  cowpea  or  bean  {Vigna  sinensis),'' ]ack  bean  (Cana- 
valia  ensiformis),  locust  bean  {Ceratonia  siligna)  and  hyacinth  bean,  bonavist 
or  lablab  {Dolichos  lablab). 


LEGUMINOS^ 


423 


The  adjuki  bean  (Pkaseolus  angularis)  and  mung  bean  {Phaseolus  aureus) 
are  now  grown  to  some  extent  in  this  country. 

.    Key  to  Principal  Species  of  Phaseolus 

Roots  tuberous  or  much  thickened,  P.  muUiflorus  (scarlet  runner  bean). 
Roots  fibrous. 

Seeds  flat  or  flat-oval  in  cross-section,  P.  lunatus  (Sieva  and  Lima  beans). 

Seeds  mostly  circular,  but  sometimes  flat  in   cross-section,  P.   vulgaris 
(kidney  bean). 

PHASEOLUS  MULTIFLORUS  (Scarlet  Ruimer  Bean,  Dutch  Case- 
knife  Bean,  Flowering  Bean,  or  Painted  Lady) 

These  are  perennials  which  usually  have  tall,  climbing 
stems  and  pinnately  trifoHate  leaves.  The  large  and  showy 
flowers  are  scarlet   (scarlet  runner),  or  white  (Dutch  case- 


FiG.   177. — Pistil   of  flower  of  common   bean   (Phaseolus  vulgaris).      (After 
Knuth.) 


knife),  and  form  racemes.  Pods  are  3  to  6  inches  long,  and 
curved;  the  seeds  are  large  and  plump,  flattened  or  cylindric, 
and  vary  in  color. 

The  scarlet  runner  form  is  also  known  as  the  flowering  bean 
or  painted  lady,  and  is  much  used  as  an  ornamental  vine. 
The  Dutch  case-knife  form  of  this  species — one  with  white 


424  BOTANY   OF    CROP   PLANTS 

flowers — is  grown  for  the  edible  beans.  The  Aroostook 
bush  Lima  bean  is  considered  by  Tracy  to  be  a  bush  form  of 
Phaseolus  multiflorus.  The  species  is  raised  to  some  extent 
by  the  Mexicans,  and  it  is  very  probable  that  some  at  least 
of  the  so-called  " Mexican  beans"  are  varieties  of  this  species. 
Phaseolus  multiflorus  is  a  native  of  South  America  and 
Mexico. 

PHASEOLUS  LUNATUS  (Sieva  and  Lima  Beans) 

These  vary  in  form  from  low  and  bushy  to  tall  and  cHmb- 
ing.  The  leaves  are  pinnately  trifoUate,  the  leaflets  varying 
from  narrowly  lanceolate  to  ovate.  The  flowers  are  small, 
and  in  axillary  racemes.  The  pods  are  usually  broad  and 
flat,  and  have  flattened,  variously  colored  beans. 

The  native  home  of  these  beans  is  tropical  South  America. 
They  require  higher  temperatures  than  the  varieties  of 
Phaseolus  vulgaris. 

Classifications  of  Types  of  Lima  Beans.^ — There  are  two 
general  types  of  Limas,  as  follows:  (i)  Phaseolus  lunatus, 
including  the  Sieva  or  Carolina  type  of  Lima,  and  (2)  P. 
lunatus  var.  macrocarpus,  including  the  true  Limas.  The 
latter  have  a  taller  and  much  more  robust  growth,  and 
thicker  leaflets  than  the  Sievas  or  Carolinas.  In  both 
groups  above,  there  are  pole  and  bush  forms. 

Table  Showing  Relationship  of  Types  of  Lima  Beans 

Phaseoltis  lunatus  (Sieva,  Civet,  or  Carolina  beans). 
Plants  bush  (Henderson's  Bush  Lima). 
Plants  pole-(Small  White  Lima,  Florida  Butter). 
Phaseolus  lunatus  var.  macrocarpus  (true  Limas). 

Seeds  very  flat  and  veiny;  pods  broad  and  flat,  with  tip  not  prominent 
leaflets  broad,  not  oyate,  Flat-seeded  Limas. 
Plants  bush  (Burpee's  Dwarf  Lima). 
Plants^pole  (King  of  the  Garden). 


LEGUMINOS^ 


425 


^'^•/ '9.— Types  of  Lima  beans.     A,  Potato  Lima,  pole';  B,  Sieva  type,  pole; 
C.  large,  flat  Lxma.  dwarf;  D,  Sieva  type,  dwarf.     (^Modified  after  Corbelt.) 


426  BOTANY   OF   CROP  PLANTS 

Seeds  smaller;  pods  short  and  thick,  with  prominent  tip;  leaflets  tapering, 
long  ovate.  Potato  Limas. 
Plants  bush  (Dreer's  Dwarf  Lima). 
Plants  pole  (Dreer's  Improved). 

PHASEOLUS  VULGARIS  (Kidney  Bean) 

These  are  annual  plants,  with  pinnately  trifoliate  leaves 
and  ovate  leaflets.  The  flowers  are  small,  not  over  %  inch 
across  the  wing,  and  are  white,  yellowish,  or  blue-purple. 
The  slender  -pods  vary  in  shape,  and  have  kidney-shaped 
seeds. 

This  species  is  thought  to  be  a  native  of  tropical  America. 
The  cultivated  varieties  thrive  best  where  the  growing 
season  is  warm. 

There  are,  according  to  Tracy,  145  varieties  of  kidney 
beans  in  America.  These  are  usually  divided  into  two  large 
subdivisions,  pole  and  hush.\  These  in  turn  each  possess 
green-podded  and  wax-podded  sorts.  The  bush  beans  are 
often  grouped  together  under  the  variety  P.  vulgaris  nanus. 
Most  of  our  common  garden  sorts  are  dwarf  or  bush  beans. ^ 

The  stringiness  of  bean  pods  is  due  to  strips  of  inedible, 
tough  fibers  at  the  sutures. 

Uses  of  Beans. — Beans  are  used  in  large  quantities  dried, 
and  in  the  pod  as  "green  beans."  Lima  beans  are  often 
canned  with  corn  in  succotash.  Great  quantities  of  common 
kidney  beans  are  put  up  in  the  form  of  "pork  and  beans." 
The  Mexicans  and  southwestern  Indians  raise  beans  in  large 
amounts;  beans  constitute  one  of  their  chief  articles  of  diet. 

VICIA  (Vetch,  Broad  Bean) 

Generic  Description.^ — The  Vicias  are  chmbing  or  traihng 
herbaceous  vines.     The  leaves  are  pinnate,  tendril-bearing, 

^  For  a  detailed  classification  of  American  varieties  of  beans  see  Bull.  109, 
Bureau  of  Plant  Industry,  by  W.  W.  Tracy. 


LEGUMINOS.E 


and  with  half-sagittate  or  entire 
stipules.  The  flowers  are  blue, 
violet,  yellowish,  or  white,  and 
in  axillary  racemes.  The  calyx: 
tube  is  oblique,  and  its  teeth  or 
lobes  are  about  equal,  or  the 
two  upper  ones  somewhat  longer. 
The  standard  is  notched  at  the 
tip,  and  the  wings  arc  attached 
to  the  curved  keel.  The  slamens 
are  diadelphous  (nine  and  one), 
or  monadelphous  below,  and 
have  fihform  filaments.  The 
sessile  or  stipitate  ovary  has 
numerous  ovules  and  a  slender 
style  with  a  tuft  or  ring  of  hairs 
at  its  summit  (Fig.  173,  A). 
The  pod  is  flat. 

Geographical. — There  are  more  than 
100  species  of  Vicia,  of  wide  geograph- 
ical distribution.  There  are  about  20 
wild  species  in  the  United  States. 

Key  to  Important  Species  of  Vria 

Plants  erect,  smooth,  or  only  slightly 
hairy,  seldom  tendril-bearing;  flowers 
whitish  with  dark  blue  spots  on  each 
wing,  V.fabj  (broad  or  Windsor  bean). 
Plants  weak,  usually  hair>',  tendril- 
bearing;  flowers  purplish. 
Leaves  rounded  at  tip;  flowers  many, 

in    long    one-sided    racemes    (I'ig. 

182),  V.  villosa  (hairy  vetch). 
Leaves  truncate  at  tip;   flowers  few, 

usually   two    in   each  leaf  axil,    V. 

saliva  (vetch). 


427 


Fk;.  180. — Types  of  bean  seeds. 
I,  Broad  Windsor;  2,  While 
Narrow  Field;  3,  Dutch  Case 
Knife  Pole;  4,  White  Dutch  Run- 
ner Pole;  5,  Grenells  Stringless 
Green  Pod;  6,  Lohk  Yellow  Si.x 
Weeks;  7,  Lohk  White  Pule  Lima; 
8.  Powell's  Prolific  Pole;  9,  Dreer's 
Pole  Lima;  10,  Florida  Butter 
Pole  Lima;  ir.  Yellow  Cranberry 
Bush;  12,  Horticultural  Wax; 
1,3,  Red  Mexican;  14.  French 
Kidney.  (Modifial  after  Tracy. 
U.  :S.  Dcpi.  Agri.) 


428 


BOTANY    OF    CROP    PLANTS 


Less  Commoa  Species.- -There  are  a  number  of  other  Vicia  spp.  that  arc 
cultivated  to  some  extent,  as  follows:  Narrow-leaved  vetch  (Vicia  angustijolia) 
is  a  native  of  the  eastern  United  States,  and  is  grown  somewhat  in  Georgia 


Fio.    i.Si. — Broad  or  Windsor  bean  (,\ 


as  a  hay  crop.  Black  bitter  vetch  {Vicia  ervilia)  is  an  Asiatic  species,  cultivated 
somewhat  as  a  winter  green- manure  crop  in  California.  Purple  vetch  {Vicia 
atro purpurea)  resembles  hairy  vetch  from  which  it  differs,  however,  in  being 
smooth.     It  is  cultivated  on  the  Pacific  Coast  and  in  the  South.     Scarlet 


LEGUMINOSiE  429 

vetch  (Vicia  fulgens) ,  Narhonne  vetch  (yicia  narbonnensis)  and  woolly  podded 
vetch  (Vicia  dasycarpa)  are  rather  rare  species,  cultivated  to  a  slight  degree 
on  the  Pacific  Coast. 

The  term  "vetch"  is  given  to  a  number  of  plants,  not  belonging  to  the 
genus  Vicia,  for  example:  Crown  vetch  {Coronilla  sp.),  kidney  vetch  {Anthyl- 
lis  vulneraria),  Dakota  vetch  (Hosackia  americana)  and  Lathyrus  spp. 

VICIA  FABA  (Broad  Bean,  Windsor  Bean) 

This  is  a  strong,  erect  annual,  2  to  4  feet  high  with  a  well- 
developed  primary  root  (Fig.  181).  The  leaves  are  pinnately 
compound,  and  become  blackish  on  drying.  The  inflorescence 
is  an  axillary  raceme  of  two  to  six  flowers.  The  flower  is 
white,  its  wings  marked  by  a  large  black  spot.  The  pods 
are  large  and  thick,  and  vary  considerably  in  length,  each 
bearing  a  number  of  large,  black  seeds.  The  smaller-seeded 
sorts,  sometimes  known  as  pigeon  bean,  field  bean  and  tick 
bean,  are  used  as  an  animal  food,  while  the  large-seeded 
varieties  are  used  as  human  food. 

The  home  of  the  wild  plant  from  which  the  cultivated 
varieties  are  derived  is  Algeria.  Broad  bean  is  cultivated 
chiefly  in  Canada.  It  thrives  best  where  the  summers  are 
long  and  cool. 

VICIA  SATIVA  (Common  Vetch  or  Tares) 

This  is  an  annual  climbing  plant  which  branches  freely. 
The  leaves  are  pinnately  compound  with  about  seven  pairs 
of  leaflets,  and  a  terminal  tendril.  Flowers  occur  singly  or  in 
twos  in  the  leaf  axils;  they  are  short  peduncled,  and  reddish 
purple  (rarely  white)  in  color.  The  flowers  are  cross-fer- 
tiHzed.  The  hairy  pods  have  four  or  five  smooth,  globular, 
gray  or  marbled  seeds.  The  Willamette  Valley,  Oregon, 
produces  a  large  proportion  of  the  common  vetch  seed  in  the 
United  States.  Vetch  seed  loses  its  viability  very  rapidly 
after  about  the  third  year.     The  plant  is  a  native  of  Europe. 


43 O  BOTANY   OF   CROP  PLANTS 

It  has  become  naturalized  in  many  parts  of  the  United  States, 
occurring  in  fields  and  waste  places.  Common  vetch  is 
sown  either  as  a  winter  or  spring  annual.  If  the  winters  are 
severe  it  is  planted  in  the  spring.  This  is  the  practice  in  the 
Northern  States.  However,  in  the  south,  where  the  winters 
are  mild,  it  is  planted  in  the  fall.  It  is  adapted  to  a  hght 
soil.  It  is  intolerant  of  a  poorly  drained  soil.  The  poorer 
soils  of  the  East,  deficient  in  hme,  will  support  a  fair  crop. 
There  are  numerous  varieties  of  the  common  vetch.  Spring 
and  winter  varieties  are  recognized.  The  white  or  pearl  vetch 
has  white  flowers  and  seeds. 

Uses. — Common  vetch  is  grown  in  the  old  country,  and  to 
an  increasing  extent  in  United  States,  as  a  hay  crop.  When 
grown  for  this  purpose  it  should  be  cut  when  in  bloom.  The 
seeds  are  sometimes  made  into  a  flour.  The  species  is  also 
being  recommended  as  a  cover  crop  for  orchards,  and  as  a 
green  manure. 

VICIA  VILLOSA  (Hairy,  Hungarian,  Russian,  Siberian,  or  Villous  Vetch) 

Hairy  vetch  (Fig.  182)  is  an  annual  or  biennial,  hairy  plant 
naturally  suited  to  cool  temperate  regions.  The  plants  may 
grow  to  a  length  of  12  feet  or  more,  but  seldom  to  any  consid- 
erable height  on  account  of  the  weak  stems.  There  is  an  ex- 
tensive and  deep  root  system  which  in  the  early  stages  of 
growth,  particularly,  constitutes  a  large  proportion  of  the  total 
weight  of  the  plant.  There  are  five  to  eight  pairs  of  leaflets, 
and  many  (about  thirty)  violet-blue,  rarely  white,  flowers  in 
one-sided  racemes.  Cross-fertiHzation  is  necessary  for  the 
normal  production  of  seeds.  Bees  are  chief  agents  in  the 
dissemination  of  pollen.  The  pods  are  smooth,  pale  in  color, 
and  contain  two  to  eight  small,  globular  black  seeds.  The 
cotyledons  remain  underground  at  germination,  as  is  the 
case  in  the  common  garden  and  field  pea.     Hairy  vetch  is  a 


LEGUMINOSvE 


431 


native  of  Europe  and  Asia.  It  is  much  hardier  than  common 
vetch,  and  consequently  can  be  grown  at  higher  latitudes. 
Moreover,  it  is  more  drought-resistant  and  tolerant  of  alkali. 


Hot  summer  weather  is  \ery  harmful  to  its  growth.  It  is 
frequently  planted  on  light,  sand\-  soils,  where  it  nKi\-  l)c 
plowed  under  as  a  green  manure. 


432  BOTANY  OF  CROP  PLANTS 

The  plant  has  a  variety  of  uses:  hay,  pasturage,  cover 
crop,  silage,  and  green  manure.  It  is  usually  cut  for  hay 
about  the  time  the  first  pods  are  full  grown.  The  quality 
of  the  hay  decreases  after  this  period. 

LATHYRUS  (Vetching,  WUd  Pea) 

This  genus  resembles  Vicla.  The  leaflets  are  broader,  as 
a  rule,  however,  the  flowers  are  larger,  and  the  stigma  is 
hairy  along  the  inner  side  (Fig.  173,  B). 

There  are  over  100  species  of  Lalhyrus,  natives  of  the 
Northern  Hemisphere  and  of  South  America.  There  are 
numerous  wild  sorts  in  the  United  States.  The  two  most 
common  species  are  Lalhyrus  odoratus,  the  common  sweet 
pea,  and  Lalhyrus  lalifolius,  the  everlasting  or  perennial  pea. 
Lalhyrus  odoralus  is  an  annual,  bearing  two  to  four  (lowers 
on  a  [)eduncle,  and  pods  4  to  5  inches  long.  The  following 
[.alhyrus  species  are  of  forage  value  and  are  now  planted  to 
some  extent  in  this  country:  L.  lingilanus  (Tangier  pea), 
L.  cicera  (flat-podded  pea)  and  L.  ochrus  (ochrus). 

TRIFOLIUM  (CIov.m) 

Generic  Description. — Representatives  of  this  group  are 
annual  (crimson  clover)  or  perennial  (white  clover)  herbs 
with  palmately  trifoliate  (hence  the  name,  Trijolium)  leaves 
(Fig.  183),  the  stipules  of  which  are  adnate  to  the  petiole. 
The  inflorescence  is  a  dense  spike  or  head.  The  flowers 
vary  in  color.  The  calyx  is  persistent,  its  teeth  nearly 
equal,  and  usually  bristle-form.  The  corolla  is  also  persist- 
ent, sometimes  grown  fast  to  the  tube  of  filaments.  The 
slamens  are  diadelphous  (nijie  and  one).  The  ovary  is  sessile 
or  stipitate,  and  few-ovuled.  The  pods  arc  small,  mem- 
branaceous, mostly  one-seeded  (rarely  more),  indehiscent  or 
opening  circularly.     The  seeds  are  small  and  kidney-shaped. 


LEGUMINOS.E  433 

Geographical. — There  are  close  to  300  species  of  Trifolium,  most  of  which 
occur  in  the  north  temperate  regions;  a  few,  however,  also  occur  in  South 
America  and  South  Africa.  They  are  distributed  from  low  to  high  altitudes. 
Besides  those  given  in  the  following  key,  two  others,  T.  suaveolens  (Shaftal 
or  Persian  clover)  and  T.  alexandrinum  (Berseem)  are  grown  to  some  extent ' 
in  the  United  States. 

Key  to  Principai-  Species  of  Trifolium 

Flowers    in    spike-like    heads,    much    longer  than   thick,    T.    incarnatum 

(crimson  or  scarlet  clover). 
Flowers  in  globular  or  ovoid  heads. 

Corolla  white  or  yellowish- white,  sometimes  touched  with  pink;  stems 

creeping,  T.  repens  (white  clover). 
Corolla  red,  red-purple,  or  rose-colored;  stems  erect  or  nearly  so. 

Flowers  pedicelled;  stipules  acuminate  (Fig,  183,  A),  T.  hybridum  (Alsike 

or  Swedish  clover). 
Flowers  sessile;  stipules  abruptly  acute  (Fig   183,  D). 

Blade  of  leaflet  marked  with  large  spot;  heads  sessile,    T.  pratense 

(red  clover). 
Blade  of  leaflet  without  spot;  heads  stalked,  T.  medium  (mammoth 
or  zigzag  clover). 

TRIFOLIUM  REPENS  (White  or  Dutch  clover) 

Description.— This  is  a  low,  smooth,  perennial  herb  aris- 
ing from  a  straight  tap  root.  The  root  system  is  shallow. 
The  plant  possesses  creeping  stems  which  develop  adventi- 
tious roots  at  the  nodes.  The  long-petioled,  trifoliate  leaves 
have  inversely  heart-shaped  or  notched  leaflets  and  narrow, 
membranous  stipules.  The  inflorescence  is  a  head  and  is 
borne  on  a  long  flower  stalk  which  arises  in  the  leaf  axils. 
The  flowers  are  small,  fragrant,  and  white  or  pinkish.  They 
are  erect  at  first,  but  become  deflexed  when  mature.  The 
visitation  of  insects  is  necessary  for  the  production  of  a 
good  crop  of  seed.  The  small  pods  are  usually  four-seeded. 
The  seeds  vary  a  great  deal  in  their  longevity.  Germination 
of  so-called  "hard  seeds"  may  be  delayed  several  years  in 
the  soil.     Such  seeds  usually  show  up  in  germination  tests. 

28 


434  BOTANY   OF   CROP  PLANTS 

Geographical,  and  Uses. — White  clover  has  become  dis- 
tributed throughout  the  greater  part  of  temperate  North 
America,  Europe,  and  Asia.  It  is  common  in  lawns,  pas- 
tures, and  meadows,  and  is  an  important  ingredient  of  lawn 
grass  mixtures.  The  only  distinct  agricultural  variety  is 
Ladino  clover  (Trifolium  repens  latum).  It  is  larger  than 
ordinary  white  clover,  and  less  resistant  to  cold. 

Environmental  Relations. — White  clover  will  withstand 
greater  temperature  extremes  than  either  red  clover  or  alsike 
clover.  It  is  naturally  suited  to  cool,  moist  regions.  It  is 
more  tolerant  of  shade  than  red  and  alsike  clovers. 

TRIFOLIUM  HYBRIDUM  (Alsike,  Alsatian,  or  Swedish  clover) 

Description. — Alsike  is  an  erect,  branching,  rather  stout, 
almost  glabrous  perennial,  i  to  3  feet  tall.  Its  hfe  period 
is  from  four  to  six  years.  There  are  many  secondary  roots 
which  soon  become  as  large  as  the  main  tap  root.  The 
leaves  are  long  and  have  greenish  veins,  long  taper-pointed 
stipules  (Fig.  1 83,  A) ,  and  obovate  leaflets.  The  plant  is  more 
leafy  than  red  clover.  The  plant  is  usually  cut  for  hay  when 
in  full  bloom.  The  flowering  heads  are  on  long  peduncles 
which  arise  from  leaf  axils.  The  flowers  are  pedicelled,  and 
white  or  pinkish.  The  pods  are  two-  to 'four-seeded.  The 
seeds  lose  their  viabiHty  rapidly  after  the  second  year. 

Geographical,  and  Uses.- — Alsike  clover  is  a  native  of 
Europe. .  It  has  been  introduced  into  this  country  for  agri- 
cultural purposes  and  has  escaped  from  cultivation,  often 
being  found  in  fields  and  waste  places.  It  is  not  a  hybrid 
between  white  clover  and  red  clover,  as  formerly  thought. 
The  plant  is  grown  in  the  same  manner  and  for  the  same 
purposes  as  red  clover.  The  plant  is  very  hardy,  more  so 
than  red  clover,  and  is  quite  frequently  mixed  with  timothy 


LEGUMINOS^ 


for  planting  at  high  altitudes  and  latitudes, 
a  honey  plant. 


435 
It  is  prized  as 


TRIFOLIUM   INCARNATUM  (Crimson,    Scarlet,   or   Italian  Clover) 

Description.— This  is  an  erect,  soft-hairy  annual,  6  to 
36  inches  high.  The  leaves  are  long  petioled;  the  stipules 
are  broad  and  with  dark  purple  margins;  the  leaflets  are 


Fig.  183. — A,  stipules  of  alsike  clover  (Trifolium  hybridum);  B,  leaf  of 
yellow  sweet  clover  (Melilotus  alba) ;  C,  leaf  of  crimson  clover  (T.  incarnatum) ; 
D,  leaf  of  common  red  clover  (T.  pratense);  E,  leaf  of  alfalfa  (Medicago 
sativa) . 


almost  sessile,  and  obovate  or  obcordate.  The  inflorescence 
is  a  terminal,  dense,  elongated,  spike-Hke  head  (Fig.  184). 
The  flowers  are  bright  crimson  (rarely  white,  yellow,  rose  or 
variegated)  and  showy.  The  seed  is  shiny  when  fresh  and 
pinkish  in  color. 


436  BOTANY  OF  CROP  PLANTS 

Geographical,  and  Uses. — Crimson  clover  is  a  native  of 
Europe.  It  has  become  naturalized  in  the  eastern  portions 
of  the  United  States,  where  it  occurs  quite  commonly  in 
waste  places.  The  plant  is  grown  in  this  country  mainly 
as  a  crop  for  hay,  forage,  or  silage.  It  also  has  some  value 
as  a  soiling  crop  and  as  a  cover  crop.  The  hay  sometimes 
proves  dangerous  to  horses,  due  to  the  tendency  of  the  hairy 
calyces  to  form  indigestible  masses  in  the  stomach  of  the 
animal,  especially  if  the  plants  are  too  ripe  when  cut.  These 
hair  balls  seldom  form  in  the  stomachs  of  cattle  and  sheep. 

Environmental  Relations. — Crimson  clover  is  less  resistant 
to  low  temperatures  than  any  of  the  other  common  clovers. 
It  is  grown  with  success  in  orchards,  because  of  its  shade 
tolerance.  Although  it  prefers  sandy  soil,  it  will  do  well  in 
soils  of  heavier  type. 

TRIFOLIUM  PRATENSE  (Common  Red  or  Purple  Clover) 

Habit,  Stems  and  Roots. — This  is  a  perennial  plant,  more 
or  less  hairy,  branching,  decumbent  or  erect,  6  to  24  inches 
tall,  rising  from  the  crown.  The  hfe  period  is  a  varietal 
character.  The  average  is  about  three  years.  It  develops 
from  a  strong  tap  root  which  possesses  an  extensive  system 
of  laterals.  The  tap  root  reaches  a  depth  of  3  or  6  feet. 
It  draws  moisture  and  mineral  nutrients  from  the  lower  soil 
layers.  In  general  there  is  about  i  pound  of  root  to  2  pounds 
of  plant  above  ground.  This  means  that  the  clover  crop 
leaves  considerable  organic  matter  in  the  soil. 

Leaves. — The  leaves  are  of  the  clover  type,  with  hairy- 
margined  leaflets  and  large  conspicuously  purple-veined 
stipules.     The  leaflets  often  bear  a  pale  spot  in  the  center. 

Inflorescence  and  Flowers. — The' termmal ' inflorescences 
are  ovate  (Fig.  184).  Each  inflorescence  has  from  35  to  150 
purple-rose  flowers.    The  second  crop  usually  has  more  flowers 


LEGUMINOS/E  437 

pcrheatl  than  Ihc  lirst  crop,  l^hij  Jlowcrs  arc  of  Ihc  ordinary 
pea  type,  except  that  the  petals  are  united  at  their  bases  and 
to  the  staminal  tube  to  form  a  corolla-tube  about  3^2  i^^ch 
long. 


(Trifiilium     incur  iiatuin), 
er  (T.  pralcnse),  on  right. 

Fruit. — The  ovary  develops  into  a  capsule,  bearing  one 
seed.  There  are  two  ovules  in  each  ovary,  but  only  one,  as 
a  rule,  matures  into  a  seed.     Lifertile  ovules  are  ciuite  com- 


438 


BOTANY    OF    CROP    PLANTS 


mon  in  red  ckn-er,  the  larger  percentage  usually  being  in 
the  first  crop.  I'liis  is  probably  one  of  the  chief  reasons  why 
the  second  cro[)  of  clover  is  more  commonly  used  for  seed. 
An  additional  advantage  in  harvesting  the  second  crop  for 
seed  rather  than  the  first  is  that  the  farmer  is  able  to  get  two 
crops  in  a  season,  for  if  the  first  crop  is  allowed  to  seed,  there 
is  insufficient  food  supply,  and  in  some  instances  a  season  too 
short,  for  the  development  of  a  vigorous  second  growth.  In 
addition  to  the  reason  given  abo\e  for  the 
relatively  hght  yield  of  seed  in  the  first  croj), 
it  is  claimed  that  pollinating  insects  are  not 
abundant  enough,  and  that  the  plant  is  occu- 
pied with  the  production  of  new  shoots  rather 
than  reproductive  activity.  In  general,  a 
rank-growing  plant  is  not  a  good  seed  producer. 
When  the  capsule  is  mature,  the  stylar  end 
separates  from  the  basal  part  by  an  irregular 
transverse  line.  The  upper  part  of  the  cap- 
sule, together  with  the  style,  comes  off  as  a 
lid  (Fig.  185),  and  the  single  seed  escapes.  The  seeds  are 
kidney-shaped,  and  yelhnv,  or  mixed  yellow  and  violet  in 
color. 

Pollination. — Red  clover  flowers  are  protandrous.  The 
work  of  Westgate  and  Coe  establishes  the  fact  that  "  red 
clover  flowers  must  be  cross-pollinated  in  order  to  set  seed 
on  a  commercial  basis."  The  pollen  must  come  from  a 
separate  plant,  for  even  when  taken  from  flowers  of  the  same 
plant,  the  percentage  of  seed  set  is  very  small.  The  bundjle- 
bee  (Bombus)  is  the  most  important  insect  visitor  of  the  red 
clover.  It  is  capable  of  pollinating  30  to  35  flowers  a  minute. 
Honey  bees  are  also  efiicient  poUinators.  When  the  bumble- 
bee lights  on  the  clover  head  and  inserts  its  proboscis  into 
the  staminal  tube,  its  weight  i)re.sses  down  on  the  keel  and 


Fig. 
Fruit  of  red 
clover  (Trifo- 
lium  pratense), 
much  enlarged. 


LEOUMiNos.ii:  439 

wings  of  the  flowcM*,  from  which  nectar  is  being  taken,  thus 
forcing  out  the  stiuma  and  anthers  up  against  the  bee's  head. 
The  stigma  becomes  dusted  with  pollen  from  another  flower 
and  the  anthers  open,  leaving  pollen  on  the  under  side  of 
the  bee's  head.  The  flower  parts  return  to  their  original 
position  when  the  bee  leaves  the  flower.  Nectar  sought  by 
the  bee  is  secreted  at  the  bases  of  the  stamens,  and  collects 
in  the  staminal  tube. 

Geographical. — Tlu;  species  is  ;i  native  of  Eurasia.  It  has  become  natural- 
ized in  the  United  States,  occurring  commonly  in  the  fields  and  meadows 
throughout  most  of  our  area. 

Environmental  Relations.— Red  clover  attains  its  best 
growth  in  humid  sections  of  the  country,  and  where  the 
summer  and  winter  temperatures  are  not  extreme.  Un- 
like alfalfa,  dry  atmospheric  conditions  arc  detrimental  to 
red  clover;  but  like  alfalfa  it  requires  lime  in  the  soil.  More- 
over, it  is  intolerant  of  a  [)()()rly  drained  soil  and  of  much 
shade. 

Mammoth  Clover.-This  clover,  sometimes  known  as 
perennial  clover,  sapling  clover,  pea-vine  clover,  and  bull 
clover,  is  a  form  of  the  ordinary  Trijolium  pratcnsc;  as 
compared  with  the  latter,  mammoth  clover  matures  later, 
has  a  more  highly  branching  tap  root,  longer  pedicels,  and 
solid  stems.     It  is  known  as  Trijolium  pratcnse  pcrcnne. 

Uses. — Common  red  clover  is  one  of  our  most  prized 
forage  and  hay  cro{)s;  it  is  also  raised  to  some  extent  as  a 
green-manure  and  cover  crop.  Its  importance  as  a  crop  in 
the  United  States  may  be  judged  from  the  fact  that  the  total 
acreage  is  about  Ave  times  that  of  alfalfa.  It  is  adapted  to 
the  humid  sections  of  the  country.  The  highest  percentage 
of  digestible  substances  occurs  in  the  plant  just,  before  full 
bloom.  The  plant  soon  becomes  tough  and  fibrous  after 
the  blooming  period. 


440 


BOTANY    OF   CROP   PLANTS 


Fi<i     18O.--A    viguiMUo    aU.iii.i    plant   sli.r.vuife;    the    "cruv.':!"    from    which 
arise  the  numerous  shoots.     {After  Ileadden,  Colo.  Agr.  Exp.  Sla.) 


LEGUMINOS^ 


441 


TRIFOLroM   MEDIUM  (Zigzag,    Medium   Red,    White,  Mammoth  or 
Meadow  Clover) 

This  is  a  perennial  clover  resembling  red  clover  {T.  pra- 
tense),  described  above.  The  plant  is  larger,  however,  its 
stems  are  more  spreading  and  bent  more  zigzag  at  the 
nodes;  the  leaflets  are  longer  and  narrower,  and  the  stipules 
longer  and  more  pointed.  The  leaflets  are  lanceolate  or 
oblong  and  not  spotted  as  in  the  red  clover.  The  flowers  are 
"bright  purple. 

This  species  is  a  native  of  Siberia  and  possibly  Europe. 
It  has  gained  entrance  into  this  country  and  occurs  here  and 
there  in  the  eastern  United  States  as 
a  ruderal. 

The  plant  is  being  grown  in  the 
same  manner  and  for  the  same  pur- 
pose as  common  red  clover. 

MEDICAGO  (Medics) 

Generic  Description.— The  medi- 
cagos  are  mostly  herbs,  sometimes 
woody  at  the  base,  as  in  common 
alfalfa,  and  very  rarely  shrubby  (one 
species  in  southern  Europe).  The 
leaves  (Fig.  183,  E)  are  pinnately 
three-foliate,  the  stipules  adnate  to 
the  petiole,  and  the.  leaflets  com- 
monly dentate,  pinnately  veined, 
with  the  veins  terminating  in  the  teeth.  The  flowers  are 
small,  yellow  or  violet,  in  axillary  heads  or  racemes.  The 
calyx  teeth  are  short,  and  about  equal  in  length.  The 
petals  are  free  from  the  staminal  tube;  the  standard  is 
obovate  or  oblong,  the  wings  oblong,  and  the  keel  short  and 
obtuse.     The  stamens  are  diadelphous  (nine  and  one) .     The 


Fig.  187. — Seed  and  pod 
of  alfalfa  (Medicago  sativa). 
X  5- 


442  BOTANY  or  CROP  PLANTS 

ovary  is  sessile  or  short-stipitate,  and  several-  or  rarely  one- 
ovuled;  it  has  a  subulate  (awl-shaped),  and  smooth  style. 
The  pods  (Fig.  187)  are  curved  or  spirally  twisted,  veiny  or 
spiny,  and  indehiscent. 

Geographical. — There  are  a  number  of  species  of  Medi- 
cago,  all  of  which  are  native  to  the  eastern  hemisphere.  They 
naturally  range  from  Eastern  Asia  to  Southern  Africa. 
There  are  seven  perennial  species  of  Medicago,  and  about  37^ 
annual  species,  one  of  which,  yellow  trefoil  (Medicago  lupu- 
lina),  has  a  biennial  or  possibly  perennial  form:  The  non- 
perennial  species  are  commonly  known  as  "bur  clovers." 
They  will  grow  naturally  as  winter  annuals. 

Key  to  Peincipal  Species  of  Medicago 

Perennial,  erect-growing  plants;  flowers  violet,  Medicago  saliva  (alfalfa). 
Annual,  low-growing  plants;  flowers  yellow. 

Pods  kidney-shaped,  without  spines,  Medicago  lupulina  (hop  clover). 
Pods  cylindrical,  with  spines. 

Stems  pubescent;  pods  33^^  to  5  millimeters  diameter;  purple  spot  in 
center  of  each  leaflet;  two  to  eight  seeds  in  each  pod,  Medicago  arabica 
(spotted  bur  clover). 
Stems  glabrous,  pods  7  to  10  millimeters  diameter;  no  purple  spot  in 
center  of  each  leaflet;  three  to  five  seeds  in  each  pod,  Medicago 
hispida  (toothed  bur  clover). 

MEDICAGO  SATIVA  (Alfalfa,  Lucerne) 

Roots. — Alfalfa  is  a  deep  feeder.  The  young  plant  usually 
sends  down  a  single  tap  root.  As  a  rule,  this  takes  a  straight 
downward  course.  Comparatively  few  side  roots  are  given 
off.  Usually,  these  are  below  the  depth  of  4  feet.  Headden 
found  in  a  plant  only  nine  months  old,  that  the  young  roots 
had  extended  to  a  depth  of  over  9  feet.  Ordinarily  the  weight 
of  roots  exceeds  weight  of  top. 

Stems. — Alfalfa  is  an  ascending  or  erect  perennial.  Its 
life  period  is  dependent  upon  environmental  conditions  and 


LEGUMINOS^  443 

the  variety.  The  average  life  is  from  five  to  seven  years. 
Fields  20  to  25  years  old  are  found  in  the  semi-arid  sections. 
At  or  near  the  ground  level,  is  a  short,  compact  stem  (crown) 
from  which  the  numerous  (20  to  50)  branches  arise  (Fig.  186). 
Bhnn  has  shown  that  there  is  a  well-defined  relationship  be- 
tween the  nature  of  the  crown  and  hardiness.  Non-hardy 
types  of  alfalfa  have  an  upright-growing  crown  with  but  few 
buds  and  shoots  developed  below  the  soil  surface.  The  crown 
of  hardy  types  is  more  spreading  and  the  numerous  buds  and 
shoots  come  from  below  the  soil  surface.  Hence  in  the  latter 
case,  the  buds  and  young  shoots  are  protected  by  the  soil 
from  winter  freezing.  These  hardy  types  are  Grimm  and 
Baltic  strains.  The  stems  of  alfalfa  are  rather  slender  and 
freely  branching.  Common  alfalfa  has  no  rootstocks. 
Some  forms  of  Medicago  falcata  possess  them,  however,  and 
they  also  occasionally  appear  in  some  variegated  types. 

"Cuttings"  of  Alfalfa. — The  number  of  "cuttings"  of 
alfalfa  depends  upon  the  length  of  the  growing  season,  and 
the  water  supply.  Three  cuttings  are  usually  made  through- 
out most  of  the  alfalfa-growing  regions  of  the  United  States. 
In  the  Imperial  Valley,  California,  ordinary  alfalfa  has 
yielded  as  many  as  nine  cuttings  in  a  year.  This  practice 
indicates  that  alfalfa  has  the  capacity  of  sending  up  numerous 
shoots  from  the  crown.  The  shoots  of  a  second  or  third 
crop  begin  to  appear  about  the  time  the  plant  is  coming  into 
bloom,  and  it  is  the  usual  practice  to  cut  the  crop  at  this 
time,  so  that  the  food  supply  that  would  normally  go  into 
developing  fruit  and  seed,  is  diverted  to  the  young  growing 
shoots  of  the  succeeding  crop.  Furthermore,  the  leaves  are 
richest  in  nutritive  substances  when  the  plant  is  in  bloom. 
The  leaves  contain  about  80  per  cent,  of  the  protein  in  the 
plant,  hence  methods  of  harvesting  should  look  toward  the 
prevention  of  their  loss.     The  different  cuttings  of  alfalfa 


444  BOTANY  OF  CROP  PLANTS 

vary  somewhat  in  quality  and  chemical  composition.  How- 
ever, more  data  are  needed  to  determine  the  relative  feeding 
value  of  the  different  cuttings. 

The  alfalfa  plant  is  a  heavy  feeder.  According  to  Ames 
and  Boltz,  a  3-ton  yield  of  alfalfa  hay  contains  163  pounds  of 
nitrogen,  17  pounds  of  phosphorus,  99  pounds  of  potassium, 
and  90  pounds  of  calcium. 

Leaves. — The  alternately  arranged  leaves  are  trifoliate 
(Fig.  183,  E).  They  are  oblong  in  general  outline  and  sharply 
toothed  along  the  margin;  the  tip  is  terminated  by  a  pro- 
jecting midrib.     The  stipules  are  prominent. 

Inflorescense. — This  is  a  dense  raceme  springing  from  the 
axils  of  the  branches. 

Flowers. — The  ordinary  color  of  the  flower  is  purple  or 
violet,  but  in  variegated  types,  may  be  blue,  green,  or  yellow. 
The  calyx  teeth  are  longer  than  the  tube  of  the  calyx.  The 
standard  is  somewhat  longer  than  the  wings,  which  in  turn 
surpass  the  keel.  The  staminal  tube  is  held  in  a  state  of 
tension  by  two  opposite  lateral  projections  on  the  inside  of 
the  keel  (Fig.  188). 

Pollination  (Fig.  188). — Alfalfa  possesses  a  mechanism  for 
the  explosive  dispersal  of  its  pollen.  When  the  edges  of  the 
keel  are  spread  apart,  the  staminal  tube  is  released,  and  both 
the  pistil  and  stamens  snap  up  against  the  standard.  The 
pollen  is  scattered  in  this  process.  The  process  is  called 
"tripping."  Alfalfa  flowers  are  usually  tripped  by  visiting 
insects,  chiefly  bumblebees  and  leaf-cutting  bees  {Mega- 
chile).  The  weight  of  an  insect  may  be  sufiicient  to  cause 
a  separation  of  the  keel  edges,  and  consequently  "tripping." 
Usually,  however,  the  separation  is  brought  about  by  the 
protrusion  of  the  insect's  proboscis  between  the  edges  of 
the  keel.  It  has  been  observed  that  alfalfa  flowers  may  be 
tripped  without  the  visitation  of  insects.     This  is  termed 


LEGITMINOS^ 


445 


"automatic"  tripping.     Humidity  and  temperature   condi- 
tions are  probable  causative  factors  in  automatic  tripping. 
Both  .  self-   and  cross-pollination  are  effective  in  alfalfa. 


tripped 


Fig.  i88. — Pollination  of  alfalfa.  A,  flower  untripped  with  calyx  and 
standard  removed;  B,  same  tripped;  C,  position  of  staminal  tube  untripped 
and  tripped.     {After  U.  S.  Deft.  Agri.) 

Self-pollination  usually  results  from  automatic  tripping. 
It  is  known  that  good  seed  crops  are  produced  in  regions 
where  tripping  insects  are  scarce.     However,  the  number 


446  BOTANY  OF  CROP  PLANTS 

of  pods  set  and  the  number  of  seeds  per  pod  are  increased 
if  cross-pollination  (xenogamy)  is  accomplished. 

Factors  Affecting  Seed  Production. — As  has  been  indi- 
cated, cross-pollination  results  in  a  greater  crop  of  seed  than 
self-pollination.  An  abundance  of  tripping  insects  may 
increase  considerably  the  seed  output;  however,  good  seed 
crops  occur  in  regions  where  tripping  insects  are  scarce. 
Seed  production  is  usually  Hght  in  humid  sections  of  the 
coimtry.  Moreover,  too  much  irrigation  water  appHed 
during  the  flowering  period  is  detrimental  to  seed  production. 
The  heaviest  yields  of  alfalfa  seed  occur  in  the  arid  sections 
of  Kansas,  Colorado,  Utah  and  Idaho.  Isolated  plants 
invariably  produce  a  greater  crop  of  seed  than  those  in  a 
thick  stand.     The  sun's  heat  favors  automatic  tripping. 

Martin  finds  that  the  setting  of  seed  pods  in  alfalfa  is 
largely  dependent  upon  the  proper  functioning  of  the  pollen. 
The  pollen  grains  require  a  certain  amount  of  water  to  germi- 
nate. When  a  pollen  grain  comes  to  the  stigma,  the  amount 
of  water  it  finds  there  depends  upon  the  moisture  delivery 
of  the  stigma  and  the  moisture  of  the  air.  The  supply  of 
water  for  germination  of  the  pollen  grains  may  be  changed 
by  increasing  the  water  in  the  soil,  or  the  atmospheric 
humidity  about  the  plant. 

Fruit. — This  is  an  indehiscent  legume,  coiled  two  or  three 
times  (Fig.  187).  There  are  one  to  eight  seeds  in  each  pod; 
they  are  kidney-shaped,  and  about  ^  inch  long.  The  seeds 
retain  their  viabihty  for  many  years. 

Germination  and  Seedling.^ — The  young  seedling  consists 
of  two  short  cotyledon?,  a  hypocotyl,  and  a  tap  root.  The 
first  foHage  leaf  is  simple,  while  the  second,  third,  and  all 
others  are  trifoliate.  There  is  soon  formed  an  erect  stem 
with  but  few  branches;  hence  the  first  growth  looks  thin. 
However,  there  spring  up  later  numerous  branches  from 


LEGUMINOS^  447 

the  lowermost  nodes  and  from  the  axils  of  the  cotyledons. 
The  result  is  a  well-developed  "crown." 

Geographical. — Common  alfalfa  is  a  native  of  temperate  western  Asia.  The 
original  home  is  probably  from  northern  India  to  the  Mediterranean  region. 
It  is  now  being  cultivated  in  many  parts  of  the  world,  and  wherever  so  culti- 
vated, frequently  escapes  and  becomes  a  ruderal. 

Types  of  Alfalfa. — Medicago  saliva  is  now  quite  generally 
considered  to  be  an  heterogeneous  species,  made  up  of  many 
strains,  varieties,  and  even  subspecies.  Westgate  holds  that 
some  of  our  hardy  strains  of  alfalfa  (Grimm,  for  example) 
owe  their  hardiness  to  the  possession  of  a  small  percentage 
of  the  "blood"  of  the  hardy  yellow-flowered  or  sickle  alfalfa 
(Medicago  falcata).  Numerous  forms  of  alfalfa  arise  where 
ordinary  alfalfa  {M.  saliva)  and  yellow-flowered  alfalfa  (M. 
falcala)  grow  together.  These  hybrid  forms  are,  of  course, 
unstable.  They  have  been  recrossed  several  times  with 
ordinary  alfalfa  and  also  among  themselves.  Such  forms 
have  been  termed  "variegated  alfalfas."  Sand  lucerne 
(Medicago  media)  is  considered  by  some  botanists  to  be  a 
natural  hybrid  between  M.  saliva  and  M.  falcala;  others 
consider  it  to  be  a  distinct  species.  Sand  lucerne  has  flower? 
ranging  from  bluish  and  purple  to  yellow,  with  numerous 
intermediate  shades.  The  seeds  are  not  as  heavy  as  those 
of  common  alfalfa.  The  plant  is  a  hardy  type.  Grimm 
alfalfa,  as  has  been  indicated,  is  quite  certainly  a  form  with 
hybrid  characteristics,  the  parents  being  common  alfalfa  and 
yellow-flowered  alfalfa.  Other  well-known  types  of  alfalfa 
are:  Turkestan,  German,  American,  Arabian,  and  Peruvian. 

Turkestan  was  secured  from  Russian  Turkestan  in  1898. 
The  water  requirement  of  the  plant  is  low,  and  it  also  pos- 
sesses an  ability  to  withstand  extremes  of  temperature. 
The  plant  is  ordinarily  a  little  smaller,  and  the  leaves  are 
narrower  and  more  hairy,  than  other  common  sorts.    German 


448  BOTANY  OF  CROP  PLANTS 

alfalfa  resembles  Turkestan.  It  is  less  hardy,  however, 
and  is  a  poorer  yielder  than  the  American  type.  The  latter 
is  the  most  common  western  alfalfa.  Arabian  alfalfas  are 
not  resistant  to  cold,  hence  they  are  restricted  to  the  warmer 
States,  particularly  Arizona,  New  Mexico,  Texas,  and 
California.  Peruvian  alfalfa  is  a  productive  sort  adapted 
to  growth  under  irrigation  in  the  southwest,  where  the  winters 
are  mild.  Brand  proposes  to  place  Peruvian  alfalfa  as  a 
distinct  variety  {Medicago  sativa  var.  polio).  It  is  taller, 
less  branched,  and  more  rapid  in  its  growth  and  recovery 
after  planting  than  common  cultivated  alfalfas.  Further- 
more the  flowers  are  sHghtly  longer,  and  the  floral  bract  is 
"longer  than  either  calyx  teeth  or  calyx  tube. 

Environmental  Relations. — Alfalfa  is  able  to  withstand 
high  temperatures  if  the  air  is  dry,  but  high  temperatures 
accompanied  by  a  humid  air  are  decidedly  injurious.  For 
this  reason,  it  is  particulary  well  adapted  to  the  semi-arid 
sections  of  the  United  States,  where  it  is  grown  both  on  irri- 
gated and  non-irrigated  land.  Its  resistance  to  low  temper- 
atures is  a  varietal  characteristic,  and  also  somewhat 
dependent  upon  cultural  operations.  Grimm  and  Baltic 
types  are  less  Hable  to  suffer  from  winter  killing  than  the 
so-called  common  alfalfas. 

The  following  data  shows  the  water  requirement  of  alfalfas, 
in  comparison  with  other  crops  (from  Briggs  and  Shantz). 

„  Water 

Crop   '  Requirement 

Millets ' 310 

Sorghums 322 

Corns 368 

Wheats 513 

Oats 597 

Potatoes 636 

Alfalfa,  Peruvian  S.  P.  I.,  (30,203) 651 

Alfalfa,  Grimm  S.  P.  I.  (25,695) 963 


LEGUMTNOS.E  449 

In  s[)ile  of  its  relatively  high  water  requirement,  alfalfa 
is  able  to  withstand  drought.  This  is  due  to  its  deep  root 
system  which  draws  upon  the  water  in  the  lower  strata  of  soil. 

Alfalfa  cannot  withstand  alkali,  and  sufTers  if  soil  drainage 
is  not  good.  The  [)lant  rec[uires  lime  in  the  soil.  The  soil 
type  has  considerable  influence  u[)on  the  form  of  the  root 
system.  A  hard  compact  soil  causes  a  more  or  less  branch- 
ing root  system,  while  in  a  loose  soil  the  tap  root  system  is 
typicall}'  de\-el()[)ed. 

Uses  and  Production.- -Alfalfa  is  the  most  imi)()rtant  hay 
crop  ''n  the  Western  States.  The  total  number  of  acres  in 
allall'a  in  the  United  States,  1909,  was  4,707,  £46;  of  this 
number,  the  Western  States  furnished  4,523,513  acres. 
The  live  leading  States,  1909,  named  in  the  order  of  their 
alfalfa  [)r()duction  were  Kansas,  Nebraska,  Colorado,  Cali- 
fornia and  Idaho. 

MEDICAGO  LUPULINA  (Hop  Clover,  Black  Medic,  Yellow  Trefoil) 

This  plant  is  usually  annual,  sometimes  perennial.  The 
stems  are  four-angled,  pubescent,  and  branched  at  the  base, 
the  branches  being  decumbent  and  spreading.  The  petioled 
leaves  have  small  obo\'ate,  oval  or  orbicular,  denticulate  or 
crenulate  leallets.  The  jlowers  are  small,  yellow,  in  den.se, 
oblong  or  cylindrical  heads.  The  pods  are  black,  curved, 
strongly  veined,  and  one-seeded. 

The  plant  is  a  native  of  Eurasia.  It  is  now  found  through- 
out the  greater  part  of  the  United  States  and  other  temperate 
regions  where  it  occurs  in  fields  and  waste  places.'  It  is 
sometimes  [)lanted  on  poor  soil,  and  has  some  promise  as 
a  green  manure. 

MEDICAGO  ARABICA     (Spotted  Bur  Clover) 

This  is  a  smooth  annual  j)lanL  with  procumbent  stems. 
The  Iciilcls  have  a  dark  purpK'  spot  in  the  center.      The  pods 


4SO 


BOTANY    OF   CROP    PLANTS 


Fig.  189. — Pods  of  10  species  of  Medicago.  Top  row,  M.  arabica  and  M. 
hispida  denticulata;  second  row,  M.  hispida  confims"*and  M.  hispida  tere- 
bellum;  third  row,  M.  muricata  and  M.  hispida  nigra;  fourth  row,  M.  ciliaris 
and  M.  echinus;  bottom  row,  M.  scutellata  and  M.  orbicularis.  (After  McKee 
and  Kicker,  U.  S.  Dept.  of  Agr.) 


LEGUMINOS/E 


451 


(Fig.  189)  are  in  long  clusters,  twisted  into  three  to  live 
spirals,  and  the  edges  bear  numerous  grooved  spines  which 
interlock.  The  seeds  are  kidney-shaped,  and  about  2)^  milli- 
meters long.  Medicago  arahica  inermis  is  a  spineless-podded 
form. 


Fk;.    190.— Toothed  bur  clover  (  M 


Spollrd  bur  clover  is  a  native  of  Europe  and  Western 
.\sia.  It  is  introduced  into  the  United  States  and  occurs  on 
the  Atlantic,  Gulf,  and  California  coasts.  It  is  being  used 
as  a  [)aslurage  crop. 


452  BOTANY  OF  CROP  PLANTS 

MEDICAGO  HISPIDA  (Toothed  Bur  Clover) 

Toothed  bur  clover  (Fig.  190)  is  a  smooth,  annual  plant 
with  decumbent  leaves.  The  leajlds  often  have  small  whitish 
and  dark  red  spots  scattered  over  the  surface,  which  disap- 
pear with  age.  T\iQfloivcrs  are  yellow.  The  pods  are  netted- 
veined,  twisted  spirally,  and  spiny.  The  seeds  are  light-  to 
brownish-yellow,  kidney-shaped,  and  about  3  millimeters 
long.  Medicago  Jiisplda  reticulala  and  M.  hispida  confmis 
are  forms  with  spineless  pods.  Toothed  bur  clover,  Medi- 
cago hispida  dcnliculata,  is  native  to  the  northern  iVIediter- 
ranean  region.  It  is  the  most  common  bur  clover  grown  in 
California.  It  finds  some  use  as  a  pasture,  hay,  cover  and 
green-manure  crop. 

In  addition  to  the  two  species  of  bur  clover  given  above, 
there  are  about  35  species  that  are  not  cultivated  to  an\- 
extent.  They  are  all  native  to  the  Mediterranean  region. 
.■\11  are  warm-climate  crops. 

MELILOTUS  (Sweet  Clover) 

Generic  Description.^ — Sweet  clovers  are  tall,  erect,  annual 
or  biennial  herbs,  with  a  fragrant  odor,  especially  when 
bruised.  The  leaves  (Fig.  183,  B)  are  pinnately  three-foliate, 
petioled,  and  possess  large  stipules  and  dentate  leaflets,  the 
veins  of  which  end  m  the  teeth.  The  flowers  are  long,  slender, 
and  in  one-sided,  axillary  racemes.  They^are  small,  and 
white  or  yellow.  The  calyx  teeth  are  short  and  about  equal. 
The  standard  is  obovate  or  oblong,  the  wings  oblong,  and 
the  keel  short  and  obtuse.  The  stamens  are  diadelphous 
(nine  and  one).  The  sessile  or  stalked  ovary  bears  a  single 
thread-Ukc  style.  The  pods  are  ovoid  or  globose,  small, 
indehiscent  or  finally  2-valved,  and  usually  one-seeded. 
Ordinarily,   all   the  seeds  of  one  year's  production  do  not 


LF.GUMINOS/E 


453 


germinate  the  first  season.     This  results  from  the  i)ro(kiction 
of  some  "hard  seeds." 

There  are  15  to  20  species  of  sweet  clover,  natives  of 
Europe,  Africa,  and  Asia.  They  are  known  by  different 
names,  such  as  wild  alfalfa,  melilot,  giant  clover,  Bokhara, 
and  sweet  clover. 


-Leaves  and  inflorescence  of  white  sweet  clover  (Melilotus  alba)  nn 
left,  and  alfalfa  (Medicago  sativa)  on  right. 


The  young  plants  resemble  alfalfa,  from  which  they  can 
be  distinguished  by  the  bitter  taste  of  the  foliage  and  the 
thicker  leaflets. 

Species  of  Melilotus.— There  are  two  common  species  of 
Melilotus:  M .  alba,  white  sweet  clover,  and  M.  officinalis, 


454  BOTANY  OF  CROP  PLANTS 

yellow  sweet  clover.  Several  other  species  of  Mclilotus 
have  been  used  agriculturally  to  some  extent;  among  such 
are  M.  indica  ("sour  clover"),  M.  altissima,  M.  gracilis, 
and  M .  speciosa. 

The  characters  of  the  two  most  im[)ortant  species  are 
arranged  in  parallel  rows  for  purposes  of  comparison. 

.1/.  alba  M.  officinalis 

Cununonly  biennial.  Commonly   annual,   sometimes   bicn- 

Flowers  white.  nial. 

Standard  slightly  longer  than  wings.       Flowers  yellow. 
I'ofls  pvoid,  glabrous.  Standard  about  equal  the  wings. 

Pods  ovoid,  often  slightly  pubescent. 

MELILOTUS  ALBA  (White  Sweet  Clover) 

Description.^-This  is  an  erect  and  smooth-stemed  bien- 
nial. It  may  reach  a  height  of  3  or  4  feet  the  first  season, 
from  seed;  the  second  season's  growth  is  much  more  vigorous, 
and  will  yield  two  crops  in  the  Northern,  and  three  in  the 
Southern  States.  New  sprouts  arise  from  above  ground 
near  the  base  of  the  plant  after  each  cutting,  and  for  this 
reason  the  plants  must  not  be  cut  too  close  to  the  ground 
line.  The  leaves  have  thick,  oblong,  finely  toothed  leaflets 
which  are  narrowed  at  the  base,  and  truncate,  notched  or 
rounded  at  the  apex.  The  racemes  are  numerous,  slender. 
and  often  one-sided.  The  flowers  are  white  and  ha\e  a 
standard  which  is  somewhat  longer  than  the  wings.  The 
pods  are  ovoid,  slightly  reticulated  (netted),  and  smooth. 

The  species  is  a  native  of  Eurasia.  It  is  a  common  road- 
side and  waste-place  weed  throughout  this  country. 

MELILOTUS  OFFICINALIS  ^Yellow  Sweet  Clover] 

Description. — This  plant  is  much  like  the  |)receding.  It 
does  not  grow   so   tall,    however,   is   less   common,   and    has 


LEGUMINOS/E  455 

yellow  flowers.  It  blooms  somewhat  earlier  than  the  white 
sweet  clover  arid  is  more  commonly  annual  in  its  habit  than 
biennial.  It  is  a  native  of  Eurasia  and,  Hke  the  preceding 
species,  has  become  naturalized  in  this  coimtry,  being  widely 
distributed  as  a  ruderal  throughout  both  the  Northern  and 
Southern  States. 

Environmental  Relations. — The  sweet  clovers  thrive  in 
both  semi-arid  and  humid  climates,  and  upon  all  types  of 
soils — heavy  and  light,  rich  and  poor,  well-drained  and  illy- 
drained.  They  are  also  drought-resistant.  It  is  being  intro- 
duced where,  for  any  reason,  alfalfa  and  clover  have  failed. 

Uses  of  Sweet  Clovers. — ^Like  other  legumes,  sweet  clover 
supports  nodules  of  bacteria  on  its  roots.  In  fact,  it  is 
nearly  as  valuable  as  alfalfa  to  plow  under  as  a  green  manure 
to  renew  the  soil.  It  makes  good  hay  when  properly 
handled,  and  for  pasturage  purposes  it  has  considerable 
value.  As  a  forage  crop,  it  can  be  utilized  where  alfalfa 
or  red  clover  cannot  be  grown  successfully.  The  plant 
becomes  coarse  and  unpalatable  soon  after  blooming,  and 
hence  it  must  be  cut  before  this  stage.  The  plants  possess 
a  bitter  principle,  cumarin,  which  may  cause  an  animal  to 
reject  them  as  food  at  first,  but  usually  the  animal  becomes 
accustomed  to  them. 

White  sweet  clover  is  much  larger  and  more  vigorous  than 
yellow,  and  consequently  is  the  one  recommended  for 
cultivation. 

SOJA  (Soy  Bean) 

Generic  Description.^ — The  soy  beans  are  prostrate  or 
erect  herbs  with  pinnately  three-,  rarely  five-  or  seven-,  foliate 
leaves.  The  flowers  are  in  short  axillary  racemes,  and  are 
purple  or  whitish.  The  pods  are  linear  or  falcate,  and  two- 
valved.     The  seeds  are  globular  and  pea-like. 


456 


BOTANY  OF  CROP  PLANTS 


There  are  between  15  and  20  species  of  Soja,  natives  of 
tropical  Asia,  Africa,  and  Australia.  There  is  only  one 
species  of  any  economic  importance.     This  is  Soja  max. 

SOJA  MAX  (Soy  Bean,  Soja  Bean,  Coflfee  Bean) 

Description. — This  is  an  erect,  bushy  appearing,  hairy 
annual,  varying  from  i3^  to  6  feet  in  height  (Fig.  192).  Unlike 
the  cowpea,  it  has  a  definite  growth,  that  is,  reaches  a  cer- 
tain size  and  matures  its  seed.     All  the  pods  of  the  soy  bean 

mature  at  one  time.  In  the 
cowpea,  new  pods  are  formed 
as  long  as  the  plant  lives. 
The  tap  root  is  short  and 
strong.  The  leaves  are  tri- 
foliate. Usually  they  have 
withered  and  fallen  by  the 
time  the  pods  are  mature, 
but  in  some  varieties  remain 
green  and  stay  on  the  plant 
for  sometime  after  the  pods 
mature.  The  flowers  are 
borne  in  axillary  clusters; 
they  are  small,  and  either 
white  or  purple  in  color. 
The  flowers  are  seK-pollinated 
as  a  rule,  and  are  completely 
self-fertile.  Occasional  cross-fertiUzation  occurs  in  the  field 
when  varieties  are  planted  very  close  together.  The  pods 
are  from  i  to  23^  inches  long,  yellowish  or  brown,  and 
covered  with  short  bristly  hairs.  As  many  as  300  to  400 
pods  have  been  found  on  one  plant,  and  each  pod  usually 
contains  two  or  three  seeds.  In  fact,  the  soy  bean  is  the 
greatest  seed  producer  of  any  legume  grown  in  temperate 


Fig.  192. — Soy  bean  (Soja    max). 
{After  Piper.) 


LEGUMINOS^  •.  457 

climates.  The  seeds  vary  greatly  in  color;  there  are  shades 
of  cream,  white,  yellow,  green,  brown,  and  black;  they  also 
vary  in  shape  from  globose  to  elliptical.  Under  the  most 
favorable  conditions,  soy  bean  seeds  do  not  retain  their 
viability  for  more  than  five  or  six  years. 

Soja  max  is  a  native  of  China  and  Japan.  The  cultivated 
varieties  are  adapted  to  the  warmer  sections  of  the  United 
States;  they  are  intolerant  of  cool  nights.  However,  there 
are  several  very  early  maturing  varieties  which  may  be  grown 
in  the  northern  tier  of  States.  The  soy  bean  will  grow  in 
moist  chmates,  and  also  manifests  drought-resistant  pro- 
pensities. The  plant  is  grown  on  a  variety  of  soil  types,  and 
will  even  produce  a  fair  crop  on  poor  soils  of  a  sandy  nature. 

Uses. — The  soy  bean  is  the  most  important  legume  in 
Asiatic  countries,  and  is  becoming  of  increasing  value  in  the 
United  States.  The  chief  product  of  the  bean  is  the  oil 
which  is  expressed  from  the  seeds.  It  is  used  in  the  manu- 
facture of  soaps,  lubricants,  water-proof  goods,  linoleum, 
rubber  substitutes  and  printing  ink;  also  in  the  preparation 
of  varnishes  and  paints,  as  a  substitute  for  linseed  oil.  After 
the  oil  is  expressed  from  the  seed,  the  "cake,"  either  un- 
ground  or  ground  into  a  meal,  is  used  as  stock  feed  or  as  a 
fertihzer.  Soy-bean  meal  is  of  considerable  value  as  human 
food.  Soy-bean  flour  is  an  important  constituent  in  many 
food  specialties  such  as  diabetic  breads,  crackers  and  bis- 
cuits. Soy-bean  flour  is  very  low  in  carbohydrates,  that 
made  from  soy-bean  cake  having  a  carbohydrate  content 
of  33.85  per  cent.,^  as  compared  with  75.35  per  cent,  in 
wheat  flour.  The  protein  content  of  flour  made  from  soy- 
bean cake  is  given  as  47.3  per  cent.,  whereas  that  of  wheat 
flour  is  but  11  per  cent.  Soy  beans  are  also  utiUzed  to 
make  a  so-called  soy-bean  milk,  which  is  valued  for  cooking 

*  Data  from  the  U.  S.  Dept.  of  Agri.  Bureau  of  Chemistry. 


4S8  BOTANY  OF  CROP  PLANTS 

purposes  by  bakers,  confectioners  and  chocolate  manufac- 
turers. The  seeds  of  soy  beans  are  sometimes  used  as  a 
substitute  for  coffee.  Soy-bean  hay  has  a  comparatively 
high  feeding  value.  It  is  recommended  as  a  pasture  for 
hogs.  The  plant  is  recognized  as  a  valuable  soiHng  and 
ensilage  crop.  Nitrogen-fixing  bacterial  nodules  occur  on 
the  roots  of  the  soy  bean. 

VIGNA  (Cowpea  and  Related  Species) 

Description. — The  "Vignas"  are  usually  climbing  or 
trailing  herbs,  sometimes  erect,  that  are  much  like  the  com- 
mon bean.  They  differ  from  the  common  1^ean  {Phaseolus 
vulgaris),  however,  mainly  in  that  the  keel  of  the  corolla  is 
short  and  merely  incurved  rather  than  spirally  coiled.  The 
leaves  are  pinnately  trifohate.  The  flowers  are  yellowish  or 
purpHsh,  in  head-shaped  or  racemose  inflorescences  at  the 
ends  of  long  pedmicles;  these  arise  in  the  axils  of  leaves. 
The  calyx  is  five-toothed.  The  stamens  are  diadelphous 
(nine  and  one).  The  ovary  is  sessile,  many-ovuled,  and 
bears  a  style  that  is  bearded  along  the  inner  side.  The 
pods  are  linear,  straight  or  slightly  curved,  and  two-valved. 
The  seeds  are  much  like  the  common  kidney  bean  in  shape 
(Fig.  193). 

All  the  Vigna  spp.  (''Vignas")  are  natives  of  warm  and 
tropical  regions,  and  consequently  they  have  been  most 
successfully  cultivated  in  the  Southern  States. 

Species. — There  are  but  three  cultivated  species  of 
"Vignas":  Vigna  sesquipedalis  (asparagus  bean),  Vigna 
catjang  (catjang),  and  Vigna  sinensis  (cowpea).  The  as- 
paragus bean  has  pendant  pods  i  to  3  feet  long,  and  kidney- 

FiG.  193. — Seeds  of  i6  varieties  of  Vigna  showing  range  in  variation  of 
shape,  size  and  color.  The  top  three  rows  are  catjangs  (Vigna  catjang),  the 
bottom  two  rows  are  asparagus  beans  (Vigna  sesquipedalis),  and  the  others  are 
cowpeas  (Vigna  sinensis).     (,After  Piper,  U.  S.  Dept.  of  Agri.) 


LEGUMINOS.E 

459 

B  2  m 

^    3    ^ 

e 

^^^ 

S 

%. 

^ 

^. 

^ 

^ 

^^•, 

(♦ 

^    e  ^ 

<? 

^ 

^    7    ^ 

^ 

h 

r^^^ 

m 

1PK 

tP^ 

0m 

r^ 

^i^  /cf^ 

^ 

^ 

m 

m 

W)  //  ^ 

«^ 

.^ 

*^w^ 

^ 

^^^  /2  "^^ 

^^^^ 

i^^^^^ 

^ 

^ 

•"/J  "-^ 

^ 

W^ 

«* 

^ 

^  /^^ 

e* 

«^ 

1^ 

?r^ 

W^^^^ 

fV^ 

^ 

mm 

w» 

f^/^^^ 

^ 

fm, 

Fin.  rov 

460 


BOTANY  OF  CROP   PLANTS 


shaped  seeds  8  to  12  millimeters  l(jng.  In  catjang,  the  pcjds 
are  small,  3  to  5  inches  long,  and  usually  erect  or  ascending 
(Fig.  194).  In  the  cowpea,  the  pods  are  8  to  12  inches  long, 
and  become  pendant  with  age.  The  cowpea  is  by  far  the 
most  important,  economically. 


Fir..    194. — .1,  flowers  and  fruit  of  catjang  (Vigna  catjaiiK')".   H-  flower 
fruit  of  cowpea  (Vigna  sinensis).     (After  U.  S.  Dcpt.  of  Aari.) 


VIGNA  SINENSIS  (Cowpea) 

Description. — The  cowpea  is  a  vigorous  annual  herb  with 
a  strong  tap  root  which  sends  out  large  side  roots  almost 
horizontally  for  i  or  2  feet  (Fig.  195).  The  greater  part  of  the 
root  system  lies  in  the  first  i}4  feet  of  soil.  The  varieties  vary 
in  habit  from  prostrate  traihng  herbs  to  tall  and  half-bushy 
forms.  The  cowpea  has  an  indeterminate  growth,  that  is, 
it  continues  to  grow  indehnitely,  providing  environmental 
conditions  are  favorable.  As  in  the  majority  of  plants 
vegetative  growth  is  favored  by  an  abundance  of  water  and 


LEGUMINOSiE 


461 


heat,  and  seed  production  is  stimulated  by  adverse  condi- 
tions. The  first  pods  may  come  to  maturity  within  seventy 
to  ninety  days  in  the  so-called  early  varieties;  on  the  other 
hand,  some  varieties  do  not  even  come  into  bloom  under 
conditions  prevailing  in  the  states  along  the  Gulf  of  Mexico. 

The  flowers  are  white  or 
pale  violet  with  three 
bracts  at  the  base  of  each 
pedicel.  The  cowpea 
flower  is  capable  of  self- 
fertilization,  and  this  is 
probably  the  most  com- 
mon occurrence  although 
the  flowers  are  often  visited 
by  honey  bees  or  bumble- 
bees. They  are  attracted 
chiefly  by  the  extra-floral 
nectaries.  The  long  pods 
(Fig.  194)  are  cylindrical, 
somewhat  curved,  and 
usually  constricted  be- 
tween the  seeds.  The 
seeds  are  numerous,  usu- 
ally bean-shaped,  spotted, 
marbled,  speckled,  or  mar- 
bled and  speckled,  and 
have  a  dark  circle  aroimd 
the  white  hilum.  Great 
variation  occurs  in  pods  and  seeds.  There  are  two  groups 
of  cowpeas  based  upon  pod  and  seed  characteristics;  kidney 
and  crowder.  The  former  have  compressed  pods  with  kidney- 
shaped  seeds;  the  latter  have  thick-walled,  cylindrical  pods 
with  globular  seeds. 


Pig.  195.- 


-Cowpea  (Vigna  sinensis). 
{After  Piper.) 


462  BOTANY  OF  CROP  PLANTS 

Environmental  Relations. — The  cowpea  is  of  tropical 
origin,  and,  hence,  is  adapted  to  those  sections  of  the  country 
with  warm  summers;  in  fact,  it  requires  more  heat  than 
corn,  and  like  corn,  does  not  thrive  where  the  nights  are  cool. 
It  is  seldom  grown  north  of  the  Ohio  River.  It  will  grow  on 
many  different  soil  types,  and  will  withstand  shading. 

Uses.^ — The  cowpea  is  of  very  great  economic  importance. 
It  is  the  chief  forage  plant  in  the  South  Central  and  South 
Atlantic  States.  The  acreage  of  the  crop  is  increasing  each 
year.  Cowpea  hay  is  prized  as  food  for  stock.  The  plant 
may  also  be  pastured  with  hogs  or  sheep  when  mature,  or 
with  cattle  before  the  peas  mature.  The  plant  is  being 
introduced  into  many  locaHties  as  a  catch  crop  or  as  a  green 
manure,  and  is  adapted  to  rotation  in  a  cropping  system. 
The  seeds  are  fed  to  poultry,  and  are  also  recommended  as 
a  food  for  man.  The  roasted  seeds  are  a  substitute  for 
coffee. 

ARACHIS  HYPOGGEA  (Peanut,  Goober) 

Habit,  Stem. — The  peanut  is  an  annual  plant  with  a  tap 
root  (Fig.  196).  The  plant  may  be  low  and  prostrate,  as  in 
the  "nmning  types,"  or  upright  and  bushy,  as  in  the  "bush 
types."     The  stems  are  thick,  angular,  branching,  and  hairy. 

Leaves. — The  leaves  are  pinnately  compound,  usually 
with  two  pairs  of  subsessile,  entire  leaflets,  and  no  tendrils; 
the  elongated  stipules  are  adnate  to  the  petiole  base. 

Flowers  (Fig.  197). — The  flowers  are  axillary,  sessile, 
and  orange-yellow  in  color.  There  are  two  sorts  of  flowers 
on  the  plant,  sterile  and  fertile.  Sterile  flowers  are  most 
numerous  in  the  upper  axils,  on  long,  slender  pedicels;  they 
have  monadelphous  stamens  (nine  united,  one  abortive) 
and  a  minute  abortive  ovary.  The  calyx  tube  is  long  and 
slender,  and  bears  on  its  rim  the  calyx  lobes,  corolla,  and 


LEGUMINOS^  463 

stamens;  the  four  superior  lobes  of  the  calyx  are  united, 
while  the  inferior  one  is  free.  The  standard  is  suborbicular, 
the  wings  oblong  and  free,  and  the  keel  incurved.  The 
ovary,  at  the  base  of  the  long,  narrow  calyx  tube,  has  one  to 
several  ovules,  and  bears  a  long  thread-like  style,  terminated 
by  a  very  small  stigma. 


Fig.  196. — Peanut  (Arachis  hypogaea).     {After  Jones.) 

Development  of  Fruit  (Fig.  196)  .—After  the  ovules  are  fer- 
tilized, the  stamens  and  corolla  fall  off;  then  the  flower  stalk 
elongates,  bends  downward,  and  carries  the  developing 
ovary  several  inches  into  the  ground.  Once  buried,  the 
ovary  ripens.  If  the  ovary  is  not  brought  underground,  it 
withers,  and  fails  to  mature. 

Fruit. — The  fruit  is  a  large,  oblong,  reticulated,  indehiscent 
legume,  with  one  to  several  ovoid  seeds.  The  "shell"  of 
the  "peanut"  is  the  pericarp;  the  thin  skin  that  surrounds 
each  seed  or  pea  ("nut")  is  the  testa.  The  cotyledons  are 
large,  and  rich  in  stored  food. 


464 


BOTANY  OF  CROP  PLANTS 


standard 


Types. — The  American  varieties  may  be  divided  into  two 
large  groups:  (i)  large-podded  and  (2)  small-podded.  Each 
of  these  is  further  subdivided  into  "bush"  or  "bunch," 
and  "running"  types.     Well-known  varieties  in  this  country 

are  Virginia  Bunch,  Virginia 
Runner,  Carolina,  Spanish, 
and  Tennessee  Red.  The 
last-named  variety  has  red- 
skinned  seeds.  The  nuts  in 
the  Spanish  variety  are 
smaller  than  those  of  the 
other  types.  Large-podded 
varieties  are  sometimes 
termed  "Jumbos." 

Environmental  Relations. 
— The  peanut  is  a  tropical 
plant.  Consequently,  it  is 
raised  where  the  growing 
season  is  long,  and  warm. 
It  succeeds  best  south  of  the 
36°  latitude. 

The  plant  is  favored  by 
ample  sunshine  and  moder- 
ate rainfall.  It  is  grown 
successfully  on  both  sandy 
and  clay  soils,  although  the 
former  are  preferred,  espe- 
cially when  the  pods  are  grown  for  the  market  and  a  bright, 
clean  appearance  is  desired. 

Uses.— Peanuts  are  largely  used  in  the  roasted  state  as 
a  human  food.  Peanut  butter  has  become  a  very  popular 
food  article.  One  bushel  of  first-class  nuts  will  yield  about 
12  pounds  of  butter.     Oil,  salted  peanuts  and  peanut  candies 


Fig.  197. — Flower  of  peanut  (Arachis 
hypogaea).      (After  Tanberl.) 


LEGUMINOSiE  465 

arc  other  products.  The  nuts  (^'goobers")  are  fed  to  hogs, 
or  the  animals  arc  turned  iti  to  pasture  on  both  the  vines 
and  nuts.  Pcanul  oil,  pressed  from  the  seeds,  is  a  nearly 
colorless  product,  which  is  employed  as  a  salad  oil,  to  a 
limited  extent  in  the  manufacture  of  soap,  and  in  the  making 
of  oleomargarines  and  similar  compounds.  Analyses  show- 
that  Spanish  and  Valencia  peanuts  are  richer  in  oil  than 
Virginia  and  other  common  types.  The  percentage  of  oil 
in  shelled  nuts  varies  from  about  45  to  50  per  cent.  Peanut 
meal,  the  product  left  after  pressing  the  oil  from  the  seeds, 
is  a  high-grade  stock  feed.  Nearly  all  peanut  oil  used  in 
this  country  is  made  in  Europe.  The  United  States  im[)orted 
1,332,108  gallons  of  the  oil  during  1914. 

LESS  IMPORTANT  LEGUMES 

The  following  list  includes  several  of  the  less  ini[)()rtant 
members,  agriculturally,  of  the  Pea  Family. 

Lupinus  (Lupines). — Annual  or  perennial  herbs  with  palmately  seven-  to 
fifteen-  foliate  leaves,  and  spikes  of  white,  yellow,  or  blue,  showy  llowers. 
They  can  grow  on  poor  sandy  soil,  but  are  little  used  in  this  country  except 
to  plow  under  as  a  green  manure.  The  species  used  for  this  purpose  are 
annuals. 

Lespedeza  striata  (Japan  Clover). — A  branched,  spreading  annual  with 
three-foliate  leaves,  short  petioles,  and  small  flowers  in  the  a.\ils  of  the  leaves. 
It  was  introduced  from  Japan  or  China  to  the  South  Atlantic  States,  where 
it  is  quite  largely  grown  for  pasture  and  hay.  It  is  adapted  to  clay  soils  and 
iloes  well  on  thin  uplands. 

Onobrychis  viciaefolia  (Sainfoin). — A  deep-rooted  perennial  witii  erect 
stems,  odd-pinnate  leaves,  si.x  to  twelve  leaflets,  and  erect,  dense  racemes  of 
rose-colored  flowers.  The  one-seeded,  brown,  lens-shaped  pods  are  indehis- 
cent.     The  seed  loses  its  viability  rapidly,  and  is  slow  to  germinate. 

The  plant  was  early  introduced  into  .\merica  from  Asia,  but  it  is  little 
grown  here.  It  is  adapted  to  dry  barren  lands  that  are  not  suited  to  clovers 
anil  alfalfas.     It  has  been  grown  with  success  on  calcareous  soils. 

Ornithopus  sativus  (Serradella).~.\  low.  branched  annual,  with  pinnately 
compound  lea\es,  and  rose  colored  or  purplish  llowers  in  umbels.  The  pods 
30 


466 


BOTANY   OF  CROP   PLANTS 


break  into  joints.     The  plant  malces  good  hay  and  thrives  on  fairly  thin  soils, 
if  not  dry.     It  grows  best  in  cool  weather,  and  is  not  very  hardy. 

Lotus   corniculatus   (Birds-foot  Trefoil). — An    annual   plant    similar    to 
clover.     The  low-spreading  stems  are  from  a  long  tap  root;  bright  yellow  or 


jr  arictimim) 


red  flowers  occur  in  small  clusters  at  the  ends  of  the  stems;  pods  are  narrow 
and  pendant.  It  is  an  Old  World  plant,  but  is  naturalized  in  the  South 
where  it  is  sown  in  mixtures  for  dry  pastures. 


LEGUMINOSiE  467 

Cicer  arietinum  (Chick-pea). — A  bushy,  hairy  annual,  i  to  2  feet  high, 
with  odd-pinnate  leaves  and  small,  white  or  pink,  solitary  flowers,  followed 
by  short,  thin  pods.  The  seeds  are  pea-like,  with  a  beak-like  projection  near 
the  hilum.  The  plant  is  grown  in  Europe,  Asia,  and  Mexico  for  its  seeds 
which  are  used  for  both  stock  and  human  food.  The  herbage  is  unfit  for 
stock  because  of  a  poisonous  principle.  The  seeds  have  been  used  as  a  coffee 
substitute. 

Trigonella  fcenum-gr cecum  (Fenugreek). — An  erect  plant  with  clover- 
like leaves,  and  long,  pointed  pods.  It  is  grown  principally  for  its  seeds, 
which  have  medicinal  properties,  and  also  as  an  orchard  green  manure.  The 
seeds  are  made  into  a  "condition  powder"  for  horses. 

References 
Bartlett,   G.:  The  Native  and  Cultivated  Vicieae  and  Phaseoleas  of  Ohio. 

Ohio  Nat.,  15:  393-404,  1914. 
Beal,  A.  C:  Evolution  and  Pollination  of  the  Sweet  Pea.     Florist's  Exch., 

32:  140-141,  1911. 
Beattie,  W.  R.:  Peanuts.     U.  S.  Dept.  Agr.  Farmers'  Bull.  356:  1-40,  1909. 

The  Peanut.     U.  S.  Dept.  Agr.  Farmers'  Bull.  431:  1-39,  1911. 
Blinn,  Philo.  :  Alfalfa — the  Relation  of  Type  to  Hardiness.     Colo.  Agr.  Exp. 

Sta.  Bull.  i8i:  1-16,  1911. 
French,    G.   T.  :  Observations   on  Medicago  lupulina  L.  Science,  n.  s.,  2, 

28:  127,  1908. 
FucsKO,  Mihaly:  tJber  die  biologischen  und  entwickelungsgeschichtlichen 

Verhaltnisse  des  Pericarps  der  Papilionaten.     Ung.  Bot.  Bl.,  8:  264-265, 

1909. 
Anatomic,  Entwickelung  und  Biologie  der  Fruchtwand  der  Papilionatae. 

Bot.  Kozlem,  8:  154-212,  1909. 
Gregory,  R.  P.:  The  Seed  Characters  of  Pisum  sativum.     New  Phytol.,  2: 

226-228,  1903. 
Handy,  R.  B.:  Peanuts:  Culture  and  Uses.     U.  S.  Dept.  Agr.  Farmers'  Bull. 

25:  1-23,  1896. 
Headden,  Wm.  p.:  Alfalfa.     Colo.  Agr.  Exp.  Sta.  Bull.  35:  1-92,  1896. 
Jones,  B.  W.:  The  Peanut  Plant.     Orange  Judd  Co.,  1885. 
KiRCHNER,  Oskar:  Uber  die  Wirkung  der  Selbstbestaubung  bei  den  Papili- 

onaceen.     Naturw.  Ztschr.  Land-u.  Forstw.  Jahrg.,  3,  Heft  1:  1-16,  1905. 
Martin,  J.  N.:  Relation  of  Moisture  to  Seed  Production  in  Alfalfa.     Iowa 

Agr.  Exp.  Sta.  Research  Bull.  23:  303-324,  1915. 
McKee,  Roland,  and  Ricker,  P.  L.:  Non-perennial  Medicagos:  the  Agro- 
nomic Value  and  Botanical  Relationship  of  the  Species.     U.  S.  Dept.  Agr. 

Bur.  Plant  Ind.  Bull.  267:  1-36,  1913. 
Oakley,  R.  A.,  and  Garver,   Samdel:    Medico  falcata,  a  Yellow- flowered 

Alfafa.     U.  S.,  Dept.  Agr.  Bull.  428:  1-70,  1917. 


468  BOTANY  OE  CROP  PLANTS 

Pammel,  Edna  C,  and  Clark,  Clarissa:  Studies  in  Variation  of  Red  Clover. 

Proc.  la.  Acad.  Sci.,  18:  47-53,  1911. 
Pammel,  L.  H.,  and  King,  Charlotte  M.:  Pollination  of  Clover.     Proc.  la. 
Acad.  Sci.,  18:  35-45,  1911. 
Pollination  of  Clover.     Contrib.  Bot.  Dept.  la.  State  College,  47: 1-45, 1911. 
Peenninger,  Ues.  :  Untersuchung  der  Fruchte  von  Phaseolus  vulgaris  L.  in 
verschiedenen  Entwickelungstadien.     Ber.  Deut.  Bot.  Ges.,  27:  227-234, 
1909. 
Piper,  C.  V.,  and  Morse,  W.  J.:  The  Soybean;  History,  Varieties,  and  Field 
Studies.     U.  S.  Dept.  Agr.  Bur.  Plant  Ind.  Bull.  197:  1-84,  1910. 
Five  Oriental  Species  of  Beans.      U.  S.  Dept.  Agr.  Bull.  119:  1-32,  1914. 
The  Bonavist,  Lablab,  or  Hyacinth  Bean.      U.  S.  Dept.  Agr.  Bull.  318: 

1-15-  1915- 
The  Soy  Bean,  with  Special  Reference  to  Its  Utilization  for  Oil,  Cake  and 

Other  Products.     U.  S.  Dept.  Agr.  Bull.  439:  1-20,  191 6. 
Piper,  C.  V.:  Agricultural  Varieties  of  the  Cowpea  and  Immediately  Related 

Species.     U.  S.  Deot.  Agr.  Bur.  Plant  Ind.  Bull.  229:  1-160,  1912. 
Soja  Max.     Jour.  Am.  Soc.  Agron.,  6:  75-84,  1914. 
Piper,  C.  V.,  Evans,  Morgan  W.,  McKee,  Roland,  and  Morse,  W.  J.: 

Alfalfa  Seed  Production;  Pollination  Studies.     U.  S.  Dept.  Agr.  Bull.  75- 

1-32,  1914. 
Piper,  C.  V.,  and  McKee,  Roland:  Vetches.     U.  S.  Dept.  Agr.  Farmers' 

Bull.  515:  1-28,  1912. 
ScoriELD,   Carl  S.:  The  Botanical  History  and  Classification  of  Alfalfa 

U.  S.  Dept.  Agr.  Bur.  Plant  Ind.  Bull.  131:  1-1-19,  1908. 
Shaw,  Thomas:  Canadian  Field  Peas.     U.  S.  Dept.  Agr.  Farmers'  Bull.  224: 

1-16,  1905. 
Tracy,  W.  W.:  American  Varieties  of  Garden  Beans.     U.  S.  Dept.  Agr.  Bur. 

Plant  Ind.  Bull.  109:  1-173,  1907. 
Westgate,  J.  M.:  Variegated  Alfalfa.     U.  S.  Dept.  Agr.  Bur.  Plant  Ind.  Bull. 

169:  1-63,  1910. 
Westgate,  J.  M.,  and  Hillman,  F.  H.:  Red  Clover.     U.  S.  Dept.  Agr. 

Farmers'  Bull.  455:  1-48,  1911. 
Westgate,  J.  M.,  and  Vinall,  H.  N.:  Sweet  Clover.     U.  S.  Dept.  Agr. 

Farmers'  Bull.  485:  7-39,  1912. 
Westgate,  J.  M.,  Coe,  H.  S.,  Wiancko,  A.  T.,  Robbins,  F.  E.,  Hughes,  H. 

D.,  Pammel,  L.  H.,  and  Martin,  J.  N.:  Red-clover  Seed  Production: 

Pollination  Studies.     U.  S.  Dept.  Agr.  Bull.  289:  1-31,  1915. 
Wight,  W.  F.:  The  History  of  the  Cowpea  (Vigna  unguiculata)  and  Its 

Introduction  into  America.     U.  S.  Dept.  Agr.  Bur.  Plant  Ind.  Bull.  102: 

43-59,  1907- 
Winton,  Kate,  B.:  Comparative  Histology  of  Alfalfa  and  Clovers.     Bot. 

Gaz.,  57:  53-63,  1914. 


CHAPTER  XXX 
LINACEiE  (Flax  FamUy) 

Habit,  Stem,  Leaf. — The  species  of  this  family  are  annual 
or  perennial  herbs,  or  shrubs.  The  plants  are  tap-rooted, 
and  each  tap  root  bears  a  number  of  slender,  lateral  branches. 
The  stems  are  single.  The  leaves  are  simple,  narrow,  nearly 
sessile,  and  usually  alternate,  although  sometimes  opposite 
(L.  catharticum) .  They  are  linear,  linear-lanceolate,  or 
oblong,  and  sharply  awn-pointed,  blunt,  or  rounded  at  the 
apex. 

Inflorescence  and  Flowers. — The  inflorescence  may  be 
a  few-flowered  corymb  or  cyme,  or  the  flowers  may  be 
more  or  less  scattered  on  the  branches.  The  flowers  (Fig. 
2i)  are  perfect,  regular,  and  five-parted  in  all  respects. 
The  sepals  are  imbricated  and  persistent.  The  petals  are 
wedge-shaped,  and  may  be  as  long  or  longer  than  the  sepals. 
They  may  be  some  shade  of  yellow  or  blue,  orange  with  rose- 
tinted  base,  red,  or  white.  The  five  stamens  have  their 
filaments  united  at  the  base.  The  outer  whorl  of  stamens 
is  wanting  or  staminodial.  The  pistil  consists  of  a  five- 
celled  ovary,  each  cell  of  which  bears  two  ovules.  The  five 
styles  may  be  free,  united  to  the  stigmas,  or  united  part  way 
from  the  base. 

Fruit.— The  flax  fruit  is  a  five-celled  capsule  with  two  seeds 
in  each  cell;  each  cell  is  partially  or  completely  divided  into 
two  by  a  false  partition  between  the  two  seeds,  thus  making 
the  capsule  apparently  ten-celled  (Fig.  21). 
469 


470  BOTANY  or  CROP  PLANTS 

The  Names  Derived  from  "Linum." — This  family  contains 
but  one  important  genus,  Linum.  The  name  Linum  is  the 
latin  for  flax.  The  word  "linen"  means  made  from  flax  or 
of  flax.  It  is  from  these  and  other  similar  foreign  names 
that  we  get  our  common  words  linen,  lint,  linseed,  and  line. 

Geographical,  and  Environmental  Relations. — The  family 
has  about  135  species,  which  are  widely  distributed  over  the 
world.  The  important  commercial  species  is  L.  usitatissi- 
mum.  All  cultivated  flax  varieties  in  this  country  are 
treated  as  belonging  to  this  one  species. 

Flax  is  raised  under  a  wide  variety  of  climatic  conditions 
and  soils.  In  regions  with  low  rainfall,  the  crop  is  of  little 
value  for  fiber,  and  hence  is  grown  chiefly  for  its  seed.  A 
fair  quality  of  fiber  flax  is  produced  in  certain  sections  of  the 
United  States  where  the  rainfall  is  25  to  30  inches.  The 
water  requirement  of  flax  is  higher  than  that  of  any  of  the 
cereals,  being  about  three  times  that  of  millet  and  sorghum. 

LINUM  USITATISSIMUM  (Common  Flax) 

Habit,  Root. — Common  flax  is  an  upright  herb  which 
under  cultivation  grows  to  a  height  of  from  i  to  4  feet 
(Fig.  199). 

It  is  a  dainty  surface  feeder  with  a  small  root  system;  this 
consists  of  a^'slender  tap  root  sparingly  supplied  with  slender 
branches  in  the  first  12  to  18  inches  of  soil.  The  tap  root 
runs  downward  vertically  to  a  depth  of  3  to  4  feet  in  some 
cases.  No  network  of  roots  is  formed  near  the  surface  of 
the  soil.  Long-stemmed  flax  as  compared  with  other  varie- 
ties appears  to  have  a  weaker  root  system  and  less  root 
penetration.  Deep  planting  is  adverse  to  root  development 
of  flax. 

Stem. — The  stem  is  simple,  erect,  and  branching  in  the 
upper  part,  rarely  at  the  base.     As  it  matures,  it  becomes 


LINACK/E 


471 


rigid,  at  the  same  time  retaining  considerable  elasticity  due 
to  the  bast  fibers. 

Flax  Fibers. — Three  tissue  areas  arc  recognizable  in  the 
stem:  i)ith,  wood,  and  bark.  The  flax  bark  contains  the 
bast   or   llax   fiber  cells.     These  bast  fibers  give  flax   straw 


its  great  financial  value  since  they  make  up  the  part  from 
which  linen  is  made.  Each  bast  fiber  is  a  single  cell,  25  to 
30  millimeters  long,  and  cylindrical  in  shape. 

Leaves,  Inflorescence    and    Flowers.— The    leaves    are 
narrow,  entire,  and   blunt  at  the  apex.     The  inflorescence 


472  BOTANY  OF  CROP  PLANTS 

is  loosely  cymosc.  The  llowers  vary  in  color  from  while  to 
deep  blue.  The  same  plant  always  bears  llowers  of  the 
same  color.  Yellow-flowered  varieties  are  not  found  in 
this  species.  The  [)etals  are  large,  conspicuous,  wedge- 
shaped,  and  about  twice  as  long  as  the  sepals. 

Pollination.— Studies  of  flax  varieties  indicate  that  there 
is  close-pollination.  Individual  flowers  produce  seed  freel\-, 
whether  associated  with  other  flowers  or  not.  Examination 
of'^flax  llowers_  at  the  proper  time  shows  anthers  in  close 
proximity  to  the  stigmas,  and  the  latter  covered  with  pollen. 

Mature  Fruit. — The  flax  fruit  (Fig.  21)  is  a  round  capsule 
known  commercially  as  the  "seed  ball."  The  seed  ball  is  com- 
posed of  live  fused  carpels.  The  balls  are  divided  into  li\e 
true  ca\ities or  locules  by  means  of  live  true  partitions  (sei)ti) 
extending  from  the  wall  (pericarp)  to  the  axis.  Each  loculc 
contains  two  seeds  and  is  divided  more  or  less  incompletely 
into  two  loculi  by  means  of  false  septi.  The  seed  balls  are 
yi  inch  or  more  in  diameter.  When  fully  ripe,  they  are 
easily  separated  into  parts  at  the  points  where  the  car[)els 
are  joined. 

Seeds. — The  seeds  vary  in  length  from  \i  to  '-  inch. 
They  are  lenticular,  compressed,  and  slightly  longer  than 
wide.  They  have  a  very  smooth,  pohshed  surface  and  vary 
in  color  from  yellow  to  dark  brown.  Light  brown  is  the 
standard  color.  A  mucilaginous  material  which  quick  I  \- 
becomes  sticky  (viscid)  in  hot  water  is  found  tilling  the 
epidermal  cells  of  the  seed.  It  is  this  substance  which  gives 
flax  its  medicinal  value.  The  embryo  is  surrounded  by  a 
thin  layer  of  endosperm  which,  in  the  mature  seed,  contains 
starch. 

Geographical.  ComnKju  flax  is  a  mitivc  of  Eiiropi;.  IL  is  now  widely  tlis- 
IribiiLcd  over  the  world,  hiring  grown  commercially  in  m;iny  countries.  Jndi;i 
is  a  heavy  producer  of  seed,  and  in  Argentina  it  is  grown  extensively  for  oil. 


LINAGES  473 

Types  and  Varieties.— There  are  large-seeded  and  small- 
seeded  varieties.  The  large-seeded  types  are  sometimes 
known  as  Sicilian  flax,  and  are  grown  almost  entirely  for 
their  seed,  rather  than  fiber;  there  are  both  blue- and  white- 
flowered  sorts.  The  small-seeded  types  are  grown  both  for 
fiber  and  seed;  there  are  both  blue-  and  white-flowered 
varieties.  The  fiber  flaxes  have  more  slender  stems,  fewer 
basal  branches,  and  a  more  compact  panicle  than  the  seed 
flaxes. 

Uses.^ — Linseed  Oil. — The  manufacture  of  linseed  oil  is 
carried  on  in  manufacturing  plants  having  investments  of 
millions  of  dollars.  The  seeds  are  crushed,  heated  to  about 
i65°F.,  placed  in  tanks  or  cylinders,  and  while  hot,  treated 
with  naphtha  to  extract  the  oil.  From  30  to  39  per  cent, 
of  the  seed  is  oil.  Linseed  oil  is  used  in  the  manufacture  of 
paints,  patent  leather  and  varnishes.  Linoleum  is  a  prepara- 
tion of  linseed  oil  which  is  hardened  by  treating  with  sulphur 
chloride  or  by  exposure  to  heated  air.  It  is  sometimes  used 
as  a  substitute  for  india-rubber.  Oil  cloth  and  other  sorts 
of  floor  cloth,  are  made  by  mixing  ground  cork  with  the 
hardened  linseed  oil  (linoleum),  and  pressing  upon  canvas. 

Oil  Cake  and  Oil  Meal. — The  residue  from  the  crushed  flax 
seeds  is  known  as  oil  cake.  It  is  sold  either  as  oil  cake  or 
ground  into  a  meal,  and  used  as  a  stock  food.  Belgium  and 
Holland  are  our  chief  customers  for  linseed-oil  cake. 

Flax  Fiber. — ^Linen  is  made  from  flax  fiber.  Our  finest 
linens  are  from  foreign  grown  flax,  the  best  of  which  is  grown 
in  Belgium  in  a  region  through  which  flows  the  River  Lip. 
The  creamy  Flemish  flax  from  which  the  finest  linen  fabrics 
are  made  is  grown  m  this  section.  Flax  fiber  is  also  utilized 
for  making  thread,  carpet  yarns,  fishing  lines,  seine  twines, 
etc.  It  is  also  employed  to  some  extent  for  upholstering, 
for  insulating  cold-storage  plants,  refrigerator  cars  and  ice 


LINAGES  475 

boxes.  A  fine  grade  of  paper  (linen  paper)  is  made  from 
linen  rags.  Linen  paper  treated  with  sulphuric  acid  gives  a 
parchment  which  takes  the  place  of  "sheep  skin." 

Preparation  of  Flax  Fiber.— Flax  plants  for  fiber  are  pulled 
by  hand  and  tied  into  small  bundles.  The  bundles  are 
shocked  and  permitted  to  cure.  After  the  seed  is  thrashed 
from  the  plants,  they  are  spread  out  thinly  on  the  ground 
and  exposed  to  the  weather  for  several  weeks.  The  exposure 
brings  about  a  partial  separation  of  the  bark  and  wood. 
This  process  is  known  as  retting.  It  is  essentially  a  fermenta- 
tion process.  Retting  is  also  carried  on  in  stagnant  water 
and  fresh  running  water.  Most  French  and  Belgium  flax  is 
retted  in  running  streams,  while  most  Irish,  flax  is  retted 
in  stagnant  water.  The  bundles  of  straw  are  then  pounded 
by  hand  or  bent  by  machinery,  until  the  fiber  is  almost 
entirely  freed  of  other  stem  parts.  The  next  treatment, 
known  as  "scutching,"  consists  in  beating  the  fibers  until  any 
fragments  of  bark  or  wood  or  course  fibers,  not  removed  in 
the  breaking  process,  are  eliminated.  Paddles,  operated 
by  hand  or  by  machinery,  are  used  in  the  scutching  process. 
The  fibers  are  sorted  and  baled,  and  kept  in  this  form  until 
ready  to  be  spun. 

Production  of  Flax.— Most  of  the  flax  for  fiber  is  grown  in 
the  European  countries.  The  United  States  is  one  of  the 
largest  seed-producing  countries  but  raises  a  very  small 
amount  of  fiber.  In  1914,  Argentina  produced  39,171,000 
bushels  of  flax  seed,  British  India  15,440,000  bushels,  and 
United  States  13,749,000  bushels.  The  large  flax  seed-pro- 
ducing States  in  1914  were  North  Dakota,  Minnesota, 
Montana,  South  Dakota,  and  Kansas. 


CHAPTER  XXXI 


RUTACEiE  (Rue  Family) 

Description. — This  family  is  represented  by  trees,  shrubs, 
and  herbs.  The  leaves  are  alternate  or  opposite,  simple  or 
compound,  exstipulate,  and  glandular-dotted.  The  glands, 
which  appear  as  translucent  dots,  are  internal.  They  vary 
somewhat  in  size  and  shape.  The  flowers  (Figs.  200  and  201) 
are  soHtary  or  in  small  axillary  or  terminal  cymes.  The  sepals 
are  four  to  five  in  number,  biit  sometimes 
absent.  There  are  as  many  petals  as 
sepals,  and  they  are  either  hypogynous  or 
perigynous.  The  separate  or  united 
stamens  are  attached  to  the  receptacle, 
and  vary  considerably  in  number;  the 
anthers  are  two-celled,  usually  versatile, 
and  introrsely  dehiscent.  The  two  to  five 
carpels  may  be  distinct,  or  united  to  form 
a  compound  pistil.  The  receptacle  is  frequently  modified 
to  form  an  annular  disk  (Fig.  201,  B).  The  fruit  is  a  capsule, 
berry,  drupe,  or  samara.  The  seeds  are  oblong  or  kidney- 
shaped,  and  have  a  straight  or  curved  embryo,  a  fleshy 
endosperm,  and  fleshy  cotyledons.  The  seeds  of  lemon  may 
germinate  in  the  fruit. 

Geographical. — The  family  is  well  represented  in  the  tropical  countries. 
There  are,  according  to  Britton  and  Brown,  about  no  genera  and  880  species. 
A  few  members  of  the  Rue  Family  are  native  to  the  United  States;  chief  of 
these  are  the  prickly  ash  (Xanthoxylum),  hop-tree  (Ptelea),  and  torch-wood 
(Amyris).  None  of  the  Citrus  species  are  native  of  America. 
476 


Fig.  200.— Floral 
diagram  of  Citrus. 
(After  Eichler.) 


RUTACE^ 


477 


Key  to  Important  Genera  of  Rutace^"^ 

Leaves  trifoliate,  Ponciriis  (trifoliate  orange). 
Leaves  unifoliate. 

Ovary  three-  to  seven-celled;  ovules  two  in  each  cell;  stigma  cavernous, 

Fortunella  (kumquat). 
Ovary  eight-  to  fifteen-celled;  usually  more  than  two  ovules  in  each  cell; 
stigma  solid,  Cilrics  (orange,  lemon,  grapefruit,  lime,  etc.). 


Fig.  201. — Sour  orange  (Citrus  aurantium).  A,  flowering  branch;  B. 
lengthwise  section  of  flower;  C,  lengthwise  section  of  fruit;  D,  seed.  (After 
Wossidlo.) 

CITRUS  (Citron,  Lemon,  Orange,  etc.) 
Habit,  Roots. — Citrus  species  are  aromatic,  mostly  thorny 
shrubs  or  small  trees  with  the  spines  disposed  singly  in  the 
leaf  axils.  The  sweet  orange  tree  is  a  surface  feeder;  almost 
its  entire  root  system  is  in  the  first  i8  inches  of  soil.  The 
sour  orange  root  system  penetrates  to  a  much  greater  depth. 
The  citrus  plant  is  different  from  most  plants  in  the  total 
absence  of  root  hairs.  Absorption  is  carried  on  by  the  fibrous 
roots  which  are  abundant  and  capable  of  rapid  growth. 
Leaves. — The  leaves  are  glandular-dotted,   winged-petio- 

^Hume  has  been  followed  largely  in  the  discussion  of  this  group. 


478  BOTANY  OF  CROP  PLANTS 

late,  glaucous,  leathery,  evergreen,  and  unifoliate  (with  the 
exception  of  Citrus  trifoliate) ;  the  leaf  stalk  is  usually  articu- 
lated to  the  blade  and  also  to  the  twig.  The  life  of  the  leaf 
depends  upon  the  kind  of  wood  upon  which  it  is  borne.  On 
the  fruiting  branches,  orange  leaves,  for  example,  remain  on 
the  tree  about  fifteen  months,  while  on  twigs  with  vigorous 
vegetative  growth  they  may  remain  on  the  tree  for  three  or 
four  years.  The  leaves  of  trifoliate  oranges  fall  in  the 
autumn.  The  aromatic  odor  of  freshly  crushed  leaves  of 
citrus  plants  is  due  to  the  numerous  glands  which  are 
scattered  over  its  surface. 

Flowers.' — The  white  or  purpHsh-pink  flowers  are  solitary, 
or  in  small  axillary  or  terminal  cjnnes  or  panicles.  The 
flowers  are  hermaphroditic;  the  calyx  is  three-  to  six- toothed; 
the  corolla  has  four  to  eight  separate  thick  segments  (petals) ; 
and  there  are  20  to  60  stamens,  united  at  their  bases  to  form 
groups;  the  ovary  possesses  8  to  75  cells  and  is  subtended  by 
a  cushion-shaped  disk  (receptacle). 

Pollination  and  Fertilization. — Some  varieties  of  citrus 
plants  require  fertilization  in  order  to  set  fruit,  while 
others  mature  parthenocarpic  ("seedless")  fruits.  Some 
varieties  of  oranges  require  cross-fertiHzation,  and  more- 
over, will  not  set  fruit  unless  pollen  is  derived  from  certain 
congenial  varieties.  Pollination  may  occur  without  the 
visitation  of  insects.  The  time  for  complete  fertihzation 
after  pollination  varies  from  thirty  hours  in  Satsuma  oranges 
to  four  weeks  in  trifoliate  oranges.  Parthenocarpic  varieties 
seldom  bear  viable  pollen.  In  navel  oranges  there  is  no 
pollen  in  the  anthers  at  flowering  time. 

Fruit. — The  fruit  is  a  modified  berry  (hesperidium) ; 
it  is  spherical  or  spheroidal  and  is  made  up  of  a  thick, 
leathery  "rind"  with  numerous  lysigenous  oil  glands,  and  a 
juicy  pulp  composed  of  numerous  stalked  "juice  sacks." 


RUTACE.E  479 

Bonavia  considers  the  rind  of  citrus  fruits  to  consist  of  a 
whorl  of  modified  leaves  that  has  grown  up  about  the  carpels. 
The  number  of  carpels  (''sections")  varies  in  the  same 
variety. 

Seeds. — There  are  from  one  to  eight  light-colored  seeds 
in  each  cell  of  the  fruit.  The  seed  coat  is  either  leathery 
or  membranous;  endosperm  is  lacking;  each  seed  has  two 
or  more  embryos  with  fleshy,  hypogean  cotyledons.  The 
polyembryonic  condition  of  citrus  fruits  is  characteristic. 
As  many  as  thirteen  seedlings  from  one  seed  have  been  noted. 
Strasburger  has  shown  that  embryos  of  citrus  seeds  may  be 
derived  from  nucellar  cells,  as  well  as  from  fertilized  ova. 
He  has  designated  such  embryos  as  "adventitious."  Hence, 
in  the  polyembryonic  seed,  there  are  two  sorts  of  embryos: 
(i)  those  formed  by  the  union  of  egg  nucleus  and  sperm 
nucleus,  true  sexual  embryos;  and  (2)  "adventitious" 
embryos  formed  by  vegetative  growth.  Obviously,  the 
seedlings  from  adventitious  embryos  may  be  used  for  propo- 
gation  with  confidence  that  they  will  come  true  to  the  plant 
which  bore  them.  Early  disintegration  of  embryo  sacs 
appears  to  be  prevalent  in  citrus  fruit.  This  may  be  one 
cause,  along  with  infertile  pollen,  of  seedless  fruits  in  this 
group. 

Geographical. — Citrus  species  are  mostly  natives  of  the  Malay  Archipelago, 
and  adjacent  Asiatic  territory.  Citrus  fruits  are  grown  only  in  those  parts  of 
the  United  States  where, there  is  an  almost  continuous  growing  season,  and 
where  freezes  seldom  occur. 

Key  to  Principal  Species  of  Citrus 

Petals  white  inside,  purplish  or  reddish  outside. 
Stamens  30  to  40;  fruit  6  to  9  inches  long,  its  skin  thick,  C  medica  (citron). 
Stamens  20  to  30;  fruit  about  3  inches  long,  its  skin  medium  thick,  C 
limonia  (lemon). 


480  BOTANY  OF  CROP  PLANTS 

Petals  white  both  on  the  inside  and  outside. 
Leaves  wingless  or  narrowly  winged. 

Fruit  small,  i^  to  23^^  inches  in  diameter,  its  skin  thin,  C.  auranlifolia 

(lime). 
Fruit  large,  its  skin  thick. 
Tree  small,  12  to  20  feet  tall;  skin  of  fruit  easily  removed,  C.  nobilis 

(king  orange). 
Tree  large,  20  to  40  feet  high;  skin  of  fruit  not  easily  removed,  C. 
sinensis  (common  sweet  orange). 
Leaves  broadly  winged. 

Fruit  large,  pale  lemon-yellow  when  ripe,  C.  grandis  (grapefruit,  pomelo, 

shaddock) . 
Fruit  medium-sized,  orange-colored  or  reddish  when  ripe,  C.  auranlium 
(sour  or  Seville  orange). 

CITRUS  MEDICA  (Citron) 

Description — This -is  a  shrub  or  small  tree  with  short, 
stout  thorns;  the  leaves  are  large,  crenate  or  serrate,  and  its 
petioles  are  wingless;  the  large  flowers  are  usually  in  clusters 
of  3  to  10;  their  petals  are  white  above,  and  reddish  purple 
below;  the  stamens  are  as  many  as  30  or  40;  the  ovary  usually 
has  from  9  to  10  locules;  the  fruit  is  large,  6  to  9  inches  long, 
rough  or  warty,  lemon-yellow  when  ripe,  its  skin  thick,  the 
pulp  scarce  and  very  acid,  and  the  juice  sacks  small  and 
slender.  In  the  "fingered  citron,"  the  fruit  segments  are 
separated  into  a  number  of  finger-like  projections. 

Geographical. — This  species  is  probably  a  native  of  India.  It  is  cultivated 
most  extensively  in  the  Mediterranean  region,  and  to  some  extent  in  this 
country. 

"Citron."^ — The  commercial  "citron"  is  the  dried  fruit  of 
Citrus  medica.  Before  the  fruit  is  candied,  it  is  placed  in 
brine  to  extract  the  undesirable  oil  in  the  skin.  The  fruit 
is  then  boiled  for  an  hour  or  so  in  a  sugar  solution  to  which 
has  been  added  some  glucose.  The  glucose  prevents  the 
product  from  becoming  too  brittle.     It  is  then  allowed  to 


RUTACE^ 


481 


stand  in  the  syrup  for  about  a  month,  and  subsequently 
boiled  in  a  pure  sugar  syrup. 

CITRUS  LIMONIA  (Lemon) 

Description. — The  lemon  tree  is  small,  from  10  to  20  feet  in 
height,  with  short,  stout  thorns;  the  leaves  are  2  to  3  inches 
long,  long-ovate,  sharp-pointed,  serrate,  and  its  petioles 
wingless;    the    large    dowers   are   axillary,    usually   solitary. 


{[■'ruin  Calif,   .l.ijr.    fix  p. 


sometimes  in  small  clusters;  their  petals  are  white  inside, 
and  purplish  above;  the  stamens  are  usually  between  20 
and  30  in  number;  the  ovary  has  7  to  10  locules.  There  are 
three  sorts  of  flowers  in  the  lemon:  (i)  perfect  flowers,  (2) 
flowers  with  rudimentary  pistils  and  normal  stamens,  and 
(3)  flowers  that  fail  to  develop  beyond  the  bud  stage.  The 
first  class  is  the  only  one  to  set  fruit.     The  fniit  is  about  3 

31 


482  BOTANY  OF  CROP  PLANTS 

inches  long,  light  yellow  when  mature,  its  skm  medium- 
thick,  the  pulp  abundant  and  acid,  and  the  juice  sacks  long 
and  pointed.  The  fruit  requires  aljout  nine  months  to 
reach  maturity. 

Geographical.— The  lemon  is  probably  a  native  of  India.  It  is  cultivated 
extensively  in  the  Mediterranean  region,  and  to  a  considerable  extent  in  Cali- 
fornia and  Florida. 

Colpr  of  Lemon  Fruit. — ^Lemons  are  picked  when  they 
reach  a  size  demanded  by  the  market,  regardless  of  the 
degree  of  maturity.  Hence  many  of  the  lemons,  when 
picked,  are  dark  green,  and  not  the  lemon-yellow  of  those 
we  buy  in  the  market.  Tlu-  fruit  is  colored  and  ripened  be- 
fore shipment.  If  they  arc  not  to  be  shipped  for  several 
months,  they  are  placed  in  storage  houses  ;where  coloring 
•s^rrd  ripening  goes  on  gradually.  However,'it^they  are  to  be 
shipped  soon  after  picking,  the  coloring  process  is  hastened. 
This  is  done  by  putting  them  in  "sweat  rooms"  that  are 
kept  at  a  temperature  between  90°  and  95°F.  The  proper 
color  is  obtained  by  this  treatment  w'ithin  four  to  six  days. 

Uses.— Lemons,  a  re  used  in  the  home  for  lemonade,  as  an 
ingredient  in  a  number  of  prepared  foods,  as  a  stain-removej, 
and  as  a  bleaching  agent.  One  of  the  chief  uses  of  lenyjhs 
is  in  the  manufacture  of  lemon,  extract.  ,-      ■; -^^^ 

Lemon  Extract. — This  ranks  second  to  vanilla  extract^in 
the  quantity  consumed.  Sicily  now  produces  the  world's 
supply  of  lemon  oil.  Cull  lemons  are  utilized  for  the  pro- 
duction of  the  oil.  Lemon  extract  is  made  by  dissolving  5 
parts  of  lemon  oil  in  95  parts  of  strong  alcohol.  Lemon  oil 
is  secreted  by  special  cells  in  the  outer  surface  of  the  rmd. 
About  95  per  cent,  of  the  lemon  oil  produced  is  obtained  from 
the  lemons  b}-  the  sponge  method,  the  remainder  b}-  the 
machine  method.  There  are  two  sponge  methods,  known  as 
the  two-piece,  and  three-piece  si)onge  methods.     Tn  the  former 


RUTACE^  483 

method  the  lemons  are  cut  by  hand  into  two  pieces,  and  the 
pulp  removed;  the  rinds  are  then  thoroughly  soaked  in  water, 
and  after  standing  for  several  hours,  passed  on  to  the  spongers. 
The  apparatus  of  the  sponger  consists  of  a  round  stick  about 
I  inch  in  diameter,  placed  across  the  top  of  an  earthenware 
bowl  about  8  inches  tall  and  the  same  in  diameter,  and 
three  sponges.  A  flat  sponge  is  hung  across  the  stick,  upon 
this  another  thicker  sponge,  and  finally  a  third  above  this. 
The  third  or  upper  sponge  is  cup-shaped;  into  this  depres- 
sion, the  lemon  rind  is  inserted.  By  main  strength  the 
operator  presses  upon  the  sponge,  repeating  this  pressure, 
after  turning  the  rind  over  several  times.  Only  i  pound  of 
oil  is  secured  from  1,600  to  2,200  lemon  halves.  The  three- 
piece  method  differs  but  shghtly  from  the  preceding. 

CITRUS  AURANTIFOLIA  (Lime) 

Description.— This  is  a  small  stragghng  tree  or  shrub,  with 
numerous,  small,  very  sharp  thorns;  the  small  leaves  are 
elliptic-oval,  crenate,  glossy-green,  and  its  petioles  are  nar- 
rowly, but  distinctly,  winged;  the  flowers  are  small,  and 
usually  produced  in  clusters  of  3  to  10;  the  petals  are  white 
both  above  and  below;  the  stamens  range  from  20  to  25; 
the  ovary  commonly  has  about  10  locules;  the  fruit  is  small' 
from  i}i  to  2i^  inches  in  diameter,  oblong,  or  rounded- 
oblong  in  outline,  light  yellow  when  ripe,  its  skin  thin,  the 
pulp  abundant,  greenish  and  very  acid,  and  the  juice  sacks 
small,  oval,  and  pointed. 

Geographical.— The  lime  is  a  native  of  India  and  southeastern  Asia.  It  is 
cultivated  in  many  tropical  countries,  and  to  some  extent  in  Florida  and  the 
Keys.     The  fruit  is  used  in  the  making  of  "limeade." 

"Limequat."— The  "Hmequat"  is  a  hybrid  between  a 
kumquat  and  the  Mexican  lime. 


484  BOTANY  OF  CROP  PLANTS 

CITRUS  SINENSIS  (Common  or  Sweet  Orange) 
Description. — The  sweet  orange  tree  is  25  to  40  feet  high, 
round-topped,  and  usually  bears  slender,  flexible,  blunt 
spines;  the  leaves  are  oval  or  ovate-oblong,  and  the  petioles 
are  narrowly  winged,  articulated  both  with  the  blade  and 
the  twig;  i\iQ, flowers  occur  singly  or  in  small  cluster;  the  petals 
are  white  above  and  below;  there  are  from  20  to  25  stamens; 
the  ovary  has  10  to  14  locules;  the  fruit  is  subglobular,  light 
orange  to  reddish,  smooth,  the  pulp  abundant  and  sweet,  and 
the  juice  sacks  spindle-shaped. 

Geographical. — The  sweet  orange  is  the  most  widely  cultivated  of  all 
citrus  fruits;  it  is  probably  a  native  of  southeastern  Asia. 

Types. — There  are  a  number  of  groups  or  types  of  sweet 
oranges;  the  four  principal  ones  are  Spanish  oranges,  Med- 
iterranean oranges,  blood  oranges,  and  navel  oranges.  Spanish 
oranges  have  large,  coarse-grained  fruit.  Mediterranean 
oranges  are  of  good  quaHty  and  fine-grained.  Blood  oranges 
have  red  pulp  or  white  pulp  streaked  with  red;  the  fruit 
is  of  good  quaHty.  Navel  oranges  are  so  named  on  account 
of  the  umbilical  mark  at  the  apex  of  the  fruit.  This  mark  is 
due  to  the  protrusion  of  additional  carpels  developed  within 
the  fruit. 

Uses. — Whereas  oranges  were  once  regarded  as  luxuries, 
they  are  now  produced  in  such  quantities  and  sold  at  such 
prices  as  to  be  within  the  reach  of  the  majority  of  people. 
Oranges  are  used  mainly  as  a  fresh  dessert.  Orange  extract 
is  made  by  dissolving  orange  oil  in  strong  alcohol.  Up  to  the 
year  191 1,  almost  the  entire  world's  supply  of  orange  oil 
came  from  Sicily,  Italy  and  adjacent  parts  of  southern 
Europe.  Since  then  the  West  Indies  have  developed  the 
industry. 

The  oil  is  used  in  the  manufacture  of  perfumes,  soaps,  and 
flavoring  extracts,  and  to  a  sHght  extent  as  a  drug. 


RUTACE^  485 

Hood  and  Russell  have  recently  pointed  out  that  the  ex- 
traction of  sweet  orange  oil  is  a  commercial  possibility  in 
this  country,  and  that  waste  oranges  may  be  utilized. 

CITRUS  NOBHIS  (King  Orange) 

Description. — The  King  orange  tree  is  12  to  20  feet  tall, 
with  slender,  drooping  branches,  and  thornless,  or  with  small 
sharp  spines;  the  leaves  are  small,  lanceolate  to  oval,  and  the 
petioles  are  wingless  or  very  narrowly  winged;  the  floivers 
occur  singly  or  in  small  clusters;  the  petals  are  white  above 
and  below,  fleshy  and  recurved;  there  are  from  18  to  24 
stamens;  the  ovary  has  9  to  15  locules;  the  fruil  is  oblate, 
orange  to  reddish  in  color,  its  peel  loose  and  easily  removed, 
the  pulp  sweet  or  sub-acid,  and  the  juice  sacks  broad  and 
blunt. 

Varieties.— Ci7rw5  nohilis  var.  deliciosa  is  the  mandarin 
orange.  In  this  variety  are  included  the  tangerine  varieties, 
which  have  an  easily  removable  skin  and  segments  that  come 
apart  readily,  also  the  langelo  which  is  a  hybrid  between  the 
tangerine  and  the  Bowcn  grapefruit.  Citrus  nohilis  j^diV. 
unshiu  is  the  Satsuma  or  Unshiu  orange.  It  is  a  small, 
spineless,  dwarf  tree,  and  very  hardy. 

CITRUS  GRANDIS  (Grapefruit,  Pomelo,  Shaddock) 

Description.— This  species  is  a  large  tree,  20  to  40  feet  in 
height,  with  slender,  flexible  spines,  if  present;  the  leaves 
are  large,  ovate,  crcnate,  broadly  rounded  at  the  base,  and 
the  petioles  are  broadly  winged  and  articulated;  the  flowers 
are  borne  singly  or  in  clusters  of  2  to  20;  the  petals  are  white 
both  above  and  below;  there  are  from  20  to  25  stamens,  with 
large  linear  anthers;  the  ovary  has  from  11  to  14  locules;  the 
fruit  is  very  large,  4  to  6  inches  in  diameter,  globose,  oblate 
or  pear-shaped,  pale  lemon-yellow  when  ripe,  its  skin  smooth. 


486 


BOTANY  OF  CROV   PLANTS 


the  pulp  peculiarly  acid  or  sub-acid,  and  the  juice  sacks  large 
and  spindle-shaped. 


Fi.;.   204-   r 


A^r.  l:xp.  Slu 


Geographical. — The  species  is  a  native  of  Polynesia  and  tiie  Malay  Archi 
pclago.     It  is  now  grown  in  the  United  States. 


RUTACE^  487 

Variety  and  Name. — The  name  grapefruit  is  the  one  that 
this  species  is  known  by  commercially.  Shaddock  is  a  horti- 
cultural variety,  the  fruit  of  which  is  much  larger  than  the 
common  grapefruit.  It  is  a  coarse,  thick-skinned  fruit,  with 
thick,  leathery  septa  between  the  locules,  and  is  of  no  com- 
mercial importance.  The  name  pomelo  is  now  recognized  by 
most  horticulturists.  Grapefruit  is  a  well-known  breakfast 
fruit. 

CITRUS  AURANTIUM  (Sour  or  SeviUe  Orange) 

Description. — The  sour  orange  tree  is  20  to  30  feet  high, 
and  bears  long,  flexible,  blunt  spines;  the  leaves  are  3  to  4 
inches  long,  wedge-shaped  at  the  base,  pointed  at  the  tip, 
and  the  petioles  are  broadly  winged;  the  flowers  are  borne 
singly  or  in  small  axillary  cymes;  the  fragrant  glandular- 
dotted  petals  are  white  above  and  below;  there  are  from  20 
to  24  stamens;  the  ovary  has  6  to  14  locules;  the  Jruit  is 
globose,  orange-colored  or  reddish,  rough,  the  pulp  acid,  and 
the  juice  sacks  small  and  spindle-shaped. 

Geographical. — The  sour  orange  is  probably  a  native  of  southeastern  Asia. 
It  is  cultivated  in  the  United  States,  being  used  as  a  stock  on  which  to  bud 
other  citrus  fruits. 

Other  Species  of  Citrus. — Other  Citrus  species  of  less 
commercial  importance  in  the  United  States  are  C.  mitis, 
the  Calamondin  orange,  C.  ichangensis ,  Ichang  lemon,  and 
C.  hergamia,  bergamot. 

FORTUNELLA  (Citrus)  (Kumquat  or  Kinkan) 

Description. — The  kumquats  are  evergreen  shrubs  with 
simple,  glandular"  leaves;  the  scented  white  flowers  are  single 
or  in  clusters  of  three  or  four,  and  axillary;  the  early  flowers 
in  the  spring  are  usually  without  pistils;  there  are  four  times 
as  many  stamens  as  petals;  the  ovary  has  three  to  seven  cells, 


488 


BOTANY  OF  CROP  PLANTS 


and  each  cell  contains  two  ovules;  a  characteristic  feature  of 
the  flower  is  the  cavernous  stigma;  the  fruit  is  small,  i  to 
iH  inches  in  diameter,  its  rind  usually  thick,  fleshy,  spicy. 


and  aromatic,  its  juice  acid,  and  its  seeds  small  and  pointed ; 
there  may  be  one  or  two  crops  of  bloom,  and  fruit  in  a  growing 
season. 

Species. — The   two  most  commoh  species   of  Fortunella 
are  F.   margarita,    the   Oval  or  Nagami  kumquat,  and  F. 


RUTACEiE  489 

japonica,  the  Round  or  Marumi  kumquat.  The  former  is 
athornless  shrub  or  small  tree  with  oval  fruit,  the  latter  a 
thorny  shrub  with  globose  fruit.  F.  crassifolia  is  the  Meiwa 
kumquat,  and  F.  hindsii,  the  Hongkong  wild  kumquat. 
The  latter  is  considered  by  Swingle  to  be  the  wild  stem  form 
of  our  Citrus  species. 

Uses. — The  kumquats  are  shrubs  grown  as  -ornamentals, 
and  also  for  their  fruit,  which  is  eaten  raw  and  entire. 

PONCmUS,  (TrifoUate  Orange) 

Description. — The  trifoliate  orange  is  a  low  tree,  seldom 
over  15  feet  high;  the  older  branches  are  thorny,  the  thorns 
being  i  to  ij^  inches  long,  and  flattened  at  the  base;  the 
characteristic  deciduous  trifoliate  leaves  are  composed  of 
thin,  elliptical,  crenate  or  dentate  leaflets;  t\iQ  flowers  usually 
appear  before  the  leaves,  singly  or  in  pairs  in  the  leaf  axils; 
the  five  sepals  are  greenish  yellow  in  color,  and  pointed  at 
the  tip;  the  corolla  is  white;  the  fruit  has  a  light  orange  color, 
is  rough,  and  covered  with  short  hairs;  it  is  of  no  com- 
mercial value;  the  numerous  seeds  differ  from  those  of  other 
allies  in  being  oval,  rounded  at  one  end  and  blunt-pointed 
at  the  other.     The  pulp  is  acid,  bitter,  and  gummy. 

A  Hardy  Orange. — The  trifoliate  orange  is  a  native  of 
China  and  Japan.  It  is  the  hardiest  of  our  citrus  species, 
and  for  that  reason  has  been  used  in  crosses  with  less  hardy, 
but  more  desirable  species,  in  the  hope  that  hybrid  forms 
would  be  secured  which  would  combine  hardiness  and  de- 
sirable fruit  characters.  Hybrids  of  trifoliate  and  sweet 
oranges  are  known  as  citranges.  Varieties  of  citranges  are 
Colman,  Morton,  Rusk,  Rustic,  and  Savage. 

References 

BiERMANN,  M.:  On  the  Structure  and  Development  of  the  Fruit  of  Citrus 
Vulgaris.     Arch.  Pharm.,  235:  19-28,  1897. 


490  BOTANY  OF  CROP  PLANTS 

BoNAViA,  E.:  Oranges  and  Lemons  of  India,  vol.  i. 

CoiT,  J.  E. :  A  Study  of  the  Factors  Influencing  Seed  Formation  in  Citrus 
Fruits.     Calif.  Agr.  Exp.  Sta.  Rpt.,  105-106,  1914. 
Citrus  Fruits.     The  MacMillan  Co.,  1915. 
Hood,  S.  C,  and  Russell,  G.  A.:  The  Production  of  Sweet-orange  Oil  and 
a  New  Machine  for  Peeling  Citrus  Fruits.     U.  S.  Dept.  Agr.  Bull.  399: 
1-19,  1916. 
Hume,  H.  Harold:  Pomelos.     Fla.  Agr.  Exp.  Sta.  Bull.  58:  385-421,  1901. 
The  Kumquats.     Fla.  Agr.  Exp.  Sta.  Bull.  65:  555-566,  1902. 
The  Mandarin  Orange  Group.     Fla.  Agr.  Exp.  Sta.  Bull.  66:  571-594. 1903- 
Citrus  Fruits  and  Their  Culture.     Orange  Judd  Co.,  1913. 
Ikeda,  Tomochika:  On  the  Parthenocarpy  of  Citrus  fruits.     Jour.  Sci.  Agr. 

Soc.  Tokyo,  63,  1904. 
OsAWA,  I.:  Cytological  and  Experimental  Studies  in  Citrus.     Jour.  Col.  Agr. 

Imp.  Univ.  Tokyo,  4:  83-116,  1912. 
Strasburger,   E.:    tJber   Polyembryonie.     Jenaisch.   Zeitsch.  Naturwiss., 

12:  647-670,  1878. 
Webber,  H.  J.:  Complications  in   Citrus  Hybridization  Caused  by  Poly- 
embryony.     Science,  n.  s.,  11:  308,  1900. 


CHAPTER  XXXII 


VITACE^  (Grape  Family) 

Family  Description.— Members  of  the  grape  family  are 
either  climbers  or  erect  shrubs  with  nodose  joints.  There  is 
an  abundance  of  watery  sap.  The  leaves  are  alternate  and 
petioled,  either  simple  (Vitis) 
or  compound  {Parthenocissus) 
(Fig.  206).  The  inflores- 
cence is  commonly  a  panicle 
(Vitis)  or  a  cyme  (Partheno- 
cissus). The  flowers  (Fig. 
210)  are  small,  greenish, 
perfect  or  polygamo-dioecious 
(perfect  flowers  on  one  indi- 
vidual and  imperfect  on 
another).  The  calyx  is  en- 
tire or  four-  to  five-toothed. 
The  four  to  five  petals  are 
either  separate  or  united  and 
fall  away  very  soon  after 
development.  Stamens  are 
four  to  five  in  number  and 
opposite    the    petals.      The 

single  ovary  has  two  to  six  cells  with  one  to  two  ovules  in 
each  locule.     The  fruit  is  commonly  a  two-celled  berry. 

Geographical. — There  are  about  10  genera  and  450  species  in  this  family, 
many  of  which  are  natives  to  tropical  countries. 
491 


Fig.  206. —  Compounddigitate leaf 
of  Virginia  creeper  (Parthenocissus 
quinquefolia). 


492 


BOTANY  OF  CROP  PLANTS 


Key  to  Important  Genera 

The   three    most   important   genera   are    Vitis    (grape),    Cissus   (pepper 
vine)  and  Parthenocissus  (Virginia  Creeper  and  American  IvyJ .     These  may 
be  distinguished  as  follows  (as  far  as  our  species  are  concerned) : 
Leaves  simple  or  pinnately  compound. 

Petals  united  into  a  cap,  falling  away  without  separat- 
ing (Fig.  210),  Vitis  (grape). 
Petals  separate,  spreading,  Cissus  (pepper  vine). 
Leaves   digitately   compound,    Parthenocissus  (Virginia 
creeper,  American  ivy). 

VITIS  (Grape) 

Stems. — Grapes  are  climbing  or  woody 
vines  with  tendrils.  The  stem  is  jointed. 
The  internodes  have  a  large  pith.     In  many 

JP  species  there  is  a  woody  tissue  (diaphragm) 
at  the  nodes  separating  the  pith;  in  others 
this  woody  tissue  is  absent  (Fig.  207).  In 
pruning  the  vines,  the  practice  is  to  make 
the  cut  through  the  nodes  rather  than  through 
the  internodes;  by  cutting  through  an  inter- 
node,  the  pith  shrinks,  leaving  a  hollow  in 
which  water  may  collect  and  rotting  set  in. 
Grapes  have  a  tendency  to  produce  suckers 
and  water  sprouts.  The  former  arise  from 
below  or  near  the  surface  of  the  ground  and 
should  be  removed.  Water  sprouts  arise 
from  dormant  buds  above  ground.  They  do 
not  produce  fruit.  If  dormant  buds  de- 
velop, producing  these  sterile  shoots,  it  in- 
dicates that  there  is  not  a  sufficient  number 
of  fruit  buds  to  take  care  of  all  the  sap 
coming  to  aerial  parts.  Water  sprouts  should 
be  removed  during  winter  pruning. 

Tendrils,  morphologically,  are  modified   stems.     This  is 


Fig.  207. — Two 
types  of  grape 
stems  cut  in  me- 
dian lengthwise 
section.  A,  south- 
ern fox  grape 
(Vitis  rotundifo- 
Ha)  with  pith  con- 
tinuous at  the 
nodes;  B,  old 
world  grape  (V. 
vinif  era)  with  pith 
interrupted  at  the 
nodes.  {After 
Hedrick.) 


VITACE/E 


493 


shown  by  the  fact  that  they  sometimes  bear  small  leaves  or 
llowers.  In  the  Fox  grape  (Fig.  2c8),  there  is  either  a  tendril 
or    an    inflorescence    opposite    each    leaf.     This    continuity 


Fig.    208. — Northern  fox  grupo  (Vitis  lahrusca). 


is  somewhat  variable,  however.     In  all  other  species,  there 
are  two  successive  leaves  with  a  tendril  or  inflorescence  oppo- 


494 


BOTANY  OF  CROP   PLANTS 


Fig.    209. — Fruit-boaring  slioot  of    river-bank:  grape  (Vitis  riparia).      (.I//1' 
Hedrick.) 


VITACE^  495 

site  each,  while  the  third  leaf  is  without  a  tendril,  and  so  on, 
there  being  no  tendril  or  cluster  for  each  third  leaf  (Fig. 
209).     A  tendril  or  inflorescence  terminates  the  stem  growth. 

Flower  clusters  are  borne  on  growing  shoots.  In  the 
spring,  a  bud  sends  out  a  growth;  flower  clusters  appear  early 
near  the  base  of  this  growth,  while  the  shoot  continues  to 
grow  until  the  end  of  the  season.  Vitis  lahrusca  averages 
three  to  six  clusters  to  a  cane;  all  other  species  average  two 
to  a  cane.  This  shoot  bears  a  number  of  buds,  each  of 
which  may,  the  following  season,  produce  another  shoot,  in 
turn  bearing  fruit  clusters.  If  all  these  buds  are  allowed  to 
develop,  the  fruit  developed  on  the  shoots  will  be  very  small. 
Hence  in  practice  it  is  found  necessary,  each  year,  to  prune 
back  the  current  season's  growth,  leaving  only  a  few  buds  to 
develop  the  succeeding  year. 

Grapes  are  commonly  propagated  from  stem  cuttings. 
The  European  grape  has  been  grown  vegetatively  for  over 
5,000  years. 

Leaves.- — ^The  grape  leaf  is  simple,  palmately  lobed  or 
dentate,  alternate,  with  grooved  petiole  and  small  stipules. 
The  leaves  of  the  different  species  vary  as  to  size,  shape, 
number  of  lobes,  nature  of  petiolar  groove,   and  surface. 

Inflorescence  and  Flowers. — The  grape  inflorescence  is  a 
compact  panicle.  As  has  been  indicated,  the  clusters  are 
borne  at  the  basal  nodes  of  the  current  season's  growth, 
opposite  a  leaf  or  a  tendril.  In  Vitis  lahrusca,  there  are  from 
three  to  six  inflorescences  to  a  cane,  while  in  all  other  species 
the  average  is  two  inflorescences  per  cane. 

In  the  wild  state,  grape  vines  are  of  two  types:  some  vines 
bear  self-sterile  perfect  flowers  and  other  vines  bear  only 
staminate  flowers.  In  cultivated  forms,  there  are  two  types 
of  perfect  flowers;  those  in  which  the  stamens  are  upright 
and  those  in  which  the  stamens  are  reflexed.     In  the  first 


4g6  BOTANY  OF  CROP  PLANTS 

case,  the  pistil  is  fully  developed  and  the  pollen  potent,  while 
in  those  flowers  with  reflexed  stamens,  the  pollen  is  more  or 
less  impotent.  Flowers  without  stamens  do  not  occur. 
Among  cultivated  European  varieties,  only  perfect  flowers  are 
common.     This  has  resulted  from  selection. 


-nectar 
^land 


Fig.  2IO. — Grape  flower,  opening.   X  20. 

The  flowers  (Fig.  210)  are  hypogynous  and  regular.  The 
calyx  consists  of  a  narrow  rim  at  the  base  of  the  flower.  The 
corolla  has  five  united,  greenish  petals;  in  the  bud,  they  form 
a  cap  (Fig.  210)  over  the  stamens  and  pistils.  When  the 
flower  opens,  the  petals  become  loosened  at  the  base  but 
remain  united  by  the  tips.     Stamens  are  five  in  number  and 


VITACE^  497 

there  is  an  equal  number  of  nectar  glands  between.  The 
one  pistil  is  two-celled  and  two-ovuled.  The  fruit  is  a 
berry. 

Dorsey  has  cited  marked  variations  in  the  flowers  of  the 
genus  Vitis:  stamens  may  vary  from  three  to  nine;  petals, 
nectariferous  glands,  and  carpels  have  a  corresponding 
numerical  variation. 

Opening  of  Flower  and  Pollination. — Flower  Opening. — 
The  opening  of  the  grape  flower  is  indicated  by  the  breaking 
away  of  the  petals  at  the  base  (Fig.  2 10).  In  some  instances, 
all  the  petals  break  away  at  about  the  same  time;  at  other 
times,  one  petal  may  initiate  the. process,  and  be  followed 
by  the  others.  The  cap  of  five  petals,  adhering  at  their 
apices,  finally  falls  off.  The  rate  of  flower  opening  varies 
from  a  few  minutes  to  several  hours.  The  anthers  seldom 
open  until  the  cap  falls  off.    Most  grapes  are  insect  pollinated. 

Self -sterility. — Many  cultivated  varieties  of  grapes  are 
self-sterile;  this  is  due,  for  the  most  part,  to  impotent  pollen. 
Some  cultivated  varieties  are  perfectly  self-fertile,  others 
partially  self-fertile,  and  still  others  entirely  self-sterile. 
As  has  been  indicated,  perfect  flowers  bearing  reflexed 
stamens  usually  have  impotent  pollen.  However,  in  some 
cases,  perfect  flowers  with  erect  stamens  also  bear  impotent 
pollen.  As  a  rule,  the  self-fertile  varieties,  those  that  can 
develop  marketable  clusters  when  self -fertilized,  have  long 
stamens.  Self-sterile  varieties,  those  that  cannot  produce 
marketable  clusters  of  fruit  when  self-fertilized,  usually 
possess  short  stamens.  However,  long  stamens  and  short 
stamens  are  not  absolute  criteria  of  self-fertility  and  self- 
sterility  respectively.  With  but  few  exceptions,  the  strongly 
self-sterile  varieties  are  hybrids.  Booth  suggests  that  the 
grape  is  "now  in  a'state  of  evolution  from  an  assumed  older 
hermaphrodite  form  to  forms  which  are  essentially  staminate 
32 


498  BOTANY  OF  CROP  PLANTS 

and  pistillate."  He  finds  all  gradations  between  "pseudo- 
staminate"  and  "pseudo-pistillate"  forms  among  wild 
species. 

Grape  Pollen .^ — In  a  study  of  grape  pollen,  Booth  found 
that  self-sterile  pollen  differs  from  self-fertile  pollen.  In  the 
self-fertile  form,  the  grain  is  surrounded  by  a  mucilaginous 
substance  which  causes  them  to  stick  together;  the  grain  is 
oblong  in  shape,  symmetrical,  and  blunt  at  the  ends.  Self- 
sterile  pollen  has  no  mucilaginous  substance  about  it;  it  is 
irregular  in  shape  and  more  pointed  at  the  ends.  Self- 
fertile  and  self-fertile  pollen  may  be  mixed  in  the  same 
variety.  The  degree  of  self-sterility  or  self-fertility  seems 
to  vary  with  environmental  conditions. 

"Couloure"  of  Muscat  Grape. — This  valuable  raisin  grape 
has  a  tendency  to  drop  its  blossoms  without  setting  fruit. 
This  trouble  is  known  as  "couloure."  It  results  from  a  lack 
of  fertiHzation.  This  is  due  to  the  fact  that  in  this  variety 
stamens  are  shorter  than  the  pistil,  that  the  pollen  has  a 
tendency  to  stick  together  in  masses  which  makes  its  dis- 
tribution less  certain,  and  to  the  rather  frequent  development 
of  imperfect  pollen  grains.  The  difficulty  is  largely  overcome 
by  planting,  in  the  Muscat  vineyard,  varieties  that  produce 
an  abundance  of  viable  pollen,  and  that  blossom  at  the  same 
time  as  the  Muscat.  These  varieties  will  furnish  pollen  for 
fertilization  of  Muscat  flowers. 

Flowers  in  Wild  Grapes. — Grapes  in  the  native  condition 
differ  from  those  in  cultivation.  The  wild  forms  seldom  bear 
self-fertile  perfect  flowers.  In  these,  there  are  just  two  sorts 
of  vines:  (i)  staminate,  and  (2)  self-sterile  hermaphrodite. 
There  are  no  self-fertile  hermaphrodites.  The  staminate 
flowers  have  abortive  pistils,  and  the  so-called  pistillate  forms 
retain  their  stamens,  but  they  are  abortive. 


VITACEJE  499 

Key  to  Most  Important  Species  of  Vitis^ 

Skin  of  mature  berry  not  separating  freely  from  the  pulp,  Vitis  vinifera 

(Old  World  grape). 
Skin  of  mature  berry  separating  readily  from  the  pulp. 

Nodes  vsdthout  diaphragms  (Fig.  207,  A) ;  tendrils  forked,  VUis  rotundifolia 

(Southern  fox  grape). 
Nodes  with  diaphragms  (Fig.  207,  B);  tendrils  forked. 
Leaves  and  shoots  glabrous  at  maturity  and  without  bloom. 

Leaves  broader  than  long;  petiolar  sinus  usually  wide  and  shallow, 

V.  rupestris  (sand  grape). 
Leaves  ovate  in  outline;  petiolar  sinus  usually  medium  to  narrow, 
V.  riparia  (river  bark  grape). 
Leaves  rusty  or  white  tomentose  or  glaucous  blue  below. 

Leaves   not   covered  with   a  thick,  dense  felt-like  tomentum   when 

fully  grown,  V.  astivalis  (summer  grape). 
Leaves  covered  with  a  dense,  thick,  felt-like  tomentum  when  fully 
grown,  V.  labrusca  (Northern  fox  grape). 

Vitis  vinifera  (Old-World  Grape,  Wine  Grape,  Raisin 
Grape). — The  Old-World  grape  is  not  as  large  a  plant  as 
most  American  species.  The  leaves  are  thin,  smooth,  and 
three-  to  seven-lobed;  they  may  be  smooth  or  woolly-hairy 
when  young;  the  lobes  are  rounded  or  pointed,  and  their 
margins  coarsely  toothed.  The  oval,  oblong,  or  globular 
berries  are  in  long  and  broad  clusters. 

The  varieties  of  this  species  have  a  high  sugar  content. 
On  this  account,  they  make  better  wine  and  raisins  than 
American  varieties.  American  varieties  are  table  grapes; 
European  varieties  are  wine  and  raisin  grapes.  The  latter 
are  now  grown  in  California,  where  the  wine  and  raisin  in- 
dustries have  developed  to  considerable  importance.  V. 
vinifera  is  not  resistant  to  the  attacks  of  Phylloxera,  a  scale 
attacking  the  leaves  and  roots.  American  varieties  are 
comparatively  more  resistant  to  these  insects  and  on  this 
account  are  used  as  stocks  upon  which  European  varieties 
are  grafted. 

^The  key  is  adapted  from  "The  Grapes  of  New  York,"  by  Hedrick. 


500  BOTANY  OF  CROP  PLANTS 

Vitis  vinifera  is  probably  a  native  of  western  and  southern 
Asia. 

Vitis  rotundifolia  (Southern  Fox  Grape) .^This  is  usually 
a  very  vigorous,  high-climbing  grape,  with  hard  wood  and 
smooth  bark.  The  leaves  are  broadly  heart-shaped,  with 
coarse,  blunt  teeth,  hght  green  in  color,  smooth  above  and 
below  or  sometimes  slightly  hairy  on  the  veins  below.  The 
large,  spherical,  black  or  greenish-yellow  berries  are  in  small 
loose  clusters.  It  grows  wild  from  southern  Delaware  to 
Missouri,  Texas,  and  the  Gulf  States. 

The  varieties  of  this  species  are  known  as  Muscadine 
grapes.     One  of  the  chief  varieties  is  the  Scuppernong. 

Vitis  rupestris  (Sand  Grape). — This  is  a  low  shrub  with  small,  broadly 
beart-shaped,  slightly  lobed  leaves  with  coarsely  toothed  margins.  The 
small,  black  or  purple-black  berries  are  in  small  clusters. 

This  species  is  southern  in  its  distribution,  reaching  southern  Pennsylvania 
as  its  northernmost  limit.     It  is  very  resistant  to  rot  and  mildew  of  the  foliage. 

Vitis  riparia  (River-bank  Grape). — The  river-bank  grape  is  a  rather 
vigorous  climbing  plant  with  smooth  and  slender  twigs.  The  leaves  have 
large  stipules;  the  margin  has  sharp  teeth  that  vary  in  size.  The  berries 
are  small,  black,  coated  with  a  bloom,  and  occur  in  rather  compact,  but  small 
clusters. 

This  is  the  most  widely  distributed  and  the  hardiest  of  American  grapes. 
It  is  common  on  stream  banks  in  the  United  States  east  of  the  Rocky 
Mountains. 

Vitis  aestivalis  (Summer  Grape). — This  is  a  strong-growing  species  with 
leaves  that  are  short-stipulate,  thick,  three-  to  five-lobed,  shallowly  dentate, 
dark  green  above  and  rusty  pubescent  beneath.  The  berries  are  astringent, 
of  average  size,  and  usually  in  long  clusters. 

This  species  is  native  to  southeastern  United  States.  Its  varieties  are  wine 
grapes. 

Vitis  labrusca  (Northern  Fox  Grape). — This  is  a  stocky 
plant  with  large,  heart-shaped  leaves  which  are  either  entire 
or  three-lobed,  dark  green  above,  and  densely  pubescent 
below.  The  clusters  of  thick-skinned  berries  are  medium 
to  large. 


VITACE^  501 

By  far  the  greatest  number  of  cultivated  grapes  are  varie- 
ties of  this  species,  or  hybrids  from  it  and  other  species, 
chiefly  Viiis  vinifera,  the  Old-World  grape. 

Varieties  of  Table  Grapes. — There  are  four  very  common 
varieties  of  table  grapes: 

1.  Catawba,  hybrid  of  V.  labrusca  and  V.  vinifera. 

2.  Delaware,  hybrid  of  V.  labrusca  and  V.  bourguiniana. 

3.  Niagara,  hybrid  of  V.  labrusca  and  V.  vinifera. 

4.  Concord,  variety  of  V.  labrusca. 

Color  of  Grapes.— Varieties  of  grapes  may  be  grouped  as 
to  color  as  follows: 

1.  Berries  Purplish-black  to  Black. — America,  August 
Giant,  Bacchus,  Black  Hamburg,  Canada,  Champion, 
Concord,  Ives,  Mills,  Muscat,  Hamburg,  Norton. 

2.  Berries  Purplish-red. — Agawam,  Brighton,  Catawba, 
Delaware,  Diana,  lona,  Jefferson,  Lutie,  Massasoit,  Red 
Eagle,  Rochester,  Vergennes. 

3.  Berries  Light  Green. — Colerain,  Croton,  Diamond, 
Duchess,  Elvira,  Grein  Golden,  Lady,  Niagara,  Triumph, 

Wine  and  Raisin  Grapes. — As  has  been  indicated,  the 
European  grape  is  a  wine  and  raisin  grape.  Some  varieties 
such  as  Petite  Sirah,  Beclan,  Mondeuse,  Verdot,  Lagrain, 
Refosco,  etc.,  are  adapted  to  the  manufacture  of  dry,  white 
wines;  Grenache,  Mission,  Palomino,  and  Boal,  are  a  few 
varieties  from  which  sweet  wine  is  made;  while  some  common 
raisin  grapes  are  White  Muscat  of  Alexandria,  Malaga,  and 
Sultanina. 

Uses. — Dried  Grapes. — These  are  known  under  the  names 
"raisins,"  ''Sultanas,"  and  "English,"  "Corinth"  or  "Zanta 
currants."  Thin-skinned  varieties,  such  as  Vinifera  grapes, 
whose  seeds  do  not  adhere  to  the  pulp,  are  preferable  for 
raisins.     "Sultanas"  are  small  light-colored  raisins  made 


502  BOTANY  OF  CROP  PLANTS 

from  a  small,  seedless  grape.  "English,  "Corinth"  or 
"Zanta  currants"  are  small  dried  grapes,  grown  chiefly  in 
the  south  of  Greece,  Table  raisins  are  made  from  the  most 
select  grapes,  and  usually  dried  in  the  sun,  without  pre- 
liminary dipping.  The  lower  grades  of  grapes  that  are  made 
into  raisins  for  cooking  purposes  are  nearly  always  dipped  in 
weak  lye  before  thy  are  dried.  California  produces  almost 
all  the  raisins  of  the  United  States.  According  to  the  census 
of  1910  the  production  of  raisins  and  dried  grapes  in  the 
United  States  amounted  to  169,245,100  pounds,  of  which 
California  furnished  169,210,675  pounds. 

Wines. — There  are  two  well-known  sorts  of  wines:  (i) 
dry  wines,  and  (2)  sweet  wines.  Dry  wines  are  those  in 
which  the  grape  sugar  has  been  converted  into  alcohol 
through  fermentation.  Sweet  wines  are  those  in  which  the 
grape  sugar  has  not  been  converted  into  alcohol,  but  the 
process  of  fermentation  has  been  prevented  by  adding 
alcohol.  There  are  two  groups  of  dry  wines:  (i)  red  wines 
(clarets,  Burgundies,  etc.);  and  (2)  white  wines  (Hocks, 
Rieslings,  etc.).  Red  wines  are  made  from  colored  grapes, 
the  skins  usually  furnishing  the  coloring  matter  for  the  fer- 
menting Juice.  In  the  making  of  red  wines,  the  skins  and 
pulp  are  crushed  and  placed  in  fermenting  vats.  The  un- 
fermented  grape  juice  is  termed  "must."  Fermentation  is 
brought  about  by  the  activity  of  yeast  plants,  and  in  this 
process,  the  conversion  of  sugar  to  alcohol  takes  place. 
After  the  completion  of  fermentation,  the  wine  is  drained 
from  the  pomace  (skins  and  other  solid  material  of  the  grape) 
and  stored  in  various  sorts  of  receptacles.  A  slow  fermenta- 
tion goes  on  in  storage,  and  during  this  period,  settlings 
accumulate,  which  are  finally  removed,  leaving  the  clear 
wine  product. 

White  wines  are  made  from  white  grapes,  or  from  those 


VITACEiE  503 

colored  grapes  with  a  colorless  juice.  The  coloring  matter 
in  the  skin  is  not  permitted  to  get  into  the  juice,  as  the 
skins  are  removed  by  pressing,  and  the  juice  allowed  to 
ferment  alone. 

The  two  chief  sweet  wines  in  this  country  are  the  ports 
and  angelicas.  Port  wines  are  made  from  colored  grapes. 
The  fruit  is  crushed  and  allowed  to  ferment;  however,  the 
process  of  fermentation  is  not  allowed  to  proceed  far,  but 
is  stopped  by  the  addition  of  alcohol.  This  adding  of 
alcohol  to  stop  the  fermentation  process  is  called  "fortify- 
ing." In  the  making  of  angelica  wines,  the  grapes  are 
crushed,  pressed  immediately  to  remove  the  pomace,  and 
the  juice  permitted  to  ferment  until  the  desired  degree  of 
sweetness  is  attained,  and  then  the  process  of  fermentation 
stopped  by  "fortifying." 

Brandy. — Brandies  are  made  both  from  white  wines  and 
red  wines.  Pure  "cognac"  is  obtained  from  the  distillation 
of  French  white  wine.  The  inferior  grades  of  brandy  come 
from  the  distillation  of  inferior  sorts  of  wine. 

Vinegar. — Grape  vinegar  is  made  from  white  and  red  wines, 
giving  white  and  red  vinegars  respectively.  Many  grapes 
unsuited  for  drying,  shipping,  or  wine-making  can  be  turned 
into  excellent  vinegars. 

Other  Uses. — Grapes  are  a  common  fresh  dessert.  The 
unfermented  juice  is  sold  in  large  quantities  in  bottles.  A 
good  table  syrup  can  be  made  from  some  varieties.  The 
wood  is  sometimes  used  in  the  manufacture  of  baskets, 
furniture,  and  rustic  work.  The  plants  are  ornamental  and 
are  frequently  turned  into  arbors.  There  are  a  number 
of  by-products  from  the  grape  plant.  Brandy,  feed,  fertil- 
izers, and  acetic  acid  are  made  from  the  pomace.  Tartaric 
acid  is  manufactured  from  the  stems,  shells  and  the  "lees"  of 
wine.     The  seeds  are  used  as  a  food  for  stock  and  as  a  source 


504  BOTANY  OF  CROP  PLANTS 

of  tannin  and  grape  oil.  A  brandy  has  been  made  by  fer- 
menting the  sugary  substance  that  sticks  to  the  seeds,  and 
this  material  may  also  be  made  into  a  syrup. 

References 

Beach,  S.  A.:  Notes  on  Self-pollination  of  the  Grape.    N.  Y.  State  Agr. 
Exp.  Sta.  Ann.  Rept.  11:  597-606,  1892. 
Self-fertility  of  the  Grape.     N.  Y.  State  Agr.  Exp.  Sta.  Bull.  157:  397-441, 

1898. 
Fertilizing  Self-sterile  Grapes.    N.  Y.  State  Agr.  Exp.  Sta.  Bull.  169: 
331-371,  1899. 
Booth,  N.  O.:  A  Study  of  Grape  Pollen.     N.  Y.  Agr.  Exp.  Sta.  Bull.  224: 

291-302,  1902. 
DoRSEY,  M.  J.:  Variation  Studies  of  the  Venation  Angles  and  Leaf  Dimen- 
sions in  Vitis.     Am.  Breeders'  Assn.,  7:  227-250,  191 1. 
Variation  in  the  Floral  Structure  of  Vitis.     Bui.  Torrey  Bot.  Club,  39:  37- 

52,  1912. 
Pollen  Development  in  Vitis  with  Special  Reference  to  Sterility,     Minn. 

Agr.  Exp.  Sta.  Bull.  144:  1-60,  1914. 
Pollen  Sterility  in  Grapes.     Jour.  Hered.,  6:  243-249,  1915. 
Hedrick,  V.  P.:  The  Grapes  of  New  York.     15th  Ann.  Rept.  N.  Y.  Agr. 

Exp.  Sta.,  vol.  3,  part  2:  1-564,  1908. 
HusMANN,  George  C,  and  Dearing,  Charles:  The  Muscadine  Grapes. 

U.  S.  Dept.  Agr.  Bur.  Plant  Ind.  Bull.  273:  1-64,  1913. 
MuNSON,  T.  V. :  Investigation  and  Improvement  of  American  Grapes.   Texas 

Agr.  Exp.  Sta.  Bull.  56:  217-285,  1899. 
Rabak,  Frank:  The  Utilization  of  Waste  Raisin  Seeds.     U.  S.  Dept.  Agr., 

Bur.  Plant  Indus.  Bull.  276:  1-36,  1913. 
Reimer,  F.  C,  and  Detjen,  L.  R.:  Self -sterility  of  the  Scuppernong  and 
Other  Muscadine  Grapes.    N.  C.  Agr.  Exp.  Sta.  Bull.  209:  1-23,  1910. 


CHAPTER  XXXIII 

MALVACE^  (MaUow  FamUy) 

Habit. — Members  of  the  family  are  herbs,  shrubs,  or 
trees.  Tree  species  are  tropical.  The  mallows  are  usually 
rich  in  mucilage. 


mvolucral  bract 


s^    \  \ca\\jlc 
^pefal 


D\sU\ 


wonadeliphou^ 

.ngement  of  parts 
(After  Cook,  U.  S.  Dept.  Agri.) 


3\drx\er]6 

Fig.  211. — Diagram  showing  arrangement  of  parts  in  the  cotton  flower. 


m 


Leaves. — The  leaves  are  alternate,  and  mostly  palmately 
veined  and  palmately  lobed.  The  stipules  are  small,  narrow, 
and  deciduous. 

505 


5o6 


BOTANY  OP  CROP  PLANTS 


Flowers. — The  flowers  are  either  single  or  in  clusters,  and 
are  terminal  or  axillary.  Some  are  subtended  by  an  involu- 
cel  which  resembles  the  epicalyx  of  strawberries.  This 
involucre  (Fig.  211)  consists  of  three  or  more  bractlets,  which 
may  be  separate  or  united.  In  the  marsh  mallow  (AlihcBa), 
the  involucre  consists  of  six  to  nine  bractlets  united  at  the 


^tapntnal 
column 


Fig.  212. — Upland     cotton     (Gossypium     hirsutum).      Median     lengthwise 
section  of  flower.       X  2. 


base;  in  Abutilon,  there  is  none;  in  Hibiscus,  it  is  of  numerous 
narrow  bractlets;  and  in  cotton  (Gossypium),  there  are  three 
large  heart-shaped  bractlets  (Fig.  211).  The  flowers  are 
regular  (Fig.  212),  perfect,  often  large,  rarely  dioecious  or 
polygamous.     There  are  five  sepals  (rarely  three  or  four), 


MALVACE^  507 

more  or  less  united,  the  lobes  valvate  or  rarely  imbricate. 
There  are  five  petals,  slightly  united  at  the  base,  convolute 
in  the  bud,  and  often  contorted.  The  stamens  are  character- 
istic features  of  the  family.  They  are  numerous,  and  united 
to  form  a  long  tube  enclosing  the  styles;  the  staminal  tube 
is  united  with  the  bases  of  the  petals  (Fig.  212).  There  are 
five  more  or  less  distinct  projections  at  the  top  of  the  tube 
of  stamens;  this  seems  to  indicate  that  there  are  in  reahty 
but  five  stamens,  united  by  their  filaments,  and  branched 
above  into  numerous  stalks  bearing  pollen  sacs.  This  is 
further  evidenced  by  the  fact  that  each  stalk  bears  a  single 
pollen  sac,  a  structure  equivalent  to  one-half  of  a  typical 
anther.  The  stamen  tube  may  be  anther-bearing  at  the 
summit,  as  in  Malva,  Abutilon,  etc.,  or  anther-bearing  below 
the  summit,  as  in  Hibiscus  and  Gossypium.  The  ovary  is 
several-celled.  Usually,  there  are  as  many  styles  as  cells 
of  the  ovary;  the  styles  are  united  below,  and  distinct  above, 
and  generally  project  beyond  the  stamen  column. 

Fruit  and  Seeds. — The  fruit  is  a  several-celled  capsule 
(rarely  a  berry).  The  seeds  are  kidney-shaped,  globose  or 
obovoid,  and  have  large  cotyledons  and  either  little  or 
abundant  endosperm. 

Geographical. — Members  of  the  family  are  widely  distributed  in  tropical 
and  temperate  regions.     There  are  about  40  genera  and  800  species. 

Economic  Importance. — The  mallow  family  possesses  one 
of  our  most  valuable  economic  plants — cotton  (Gossypium). 
Cotton  is  the  chief  fiber  plant  of  the  world.  It  is  grown 
throughout  tropical  and  subtropical  regions.  Another  crop 
plant  is  okra  or  gumbo  {Hibiscus  esculentus).  Althcea 
officinalis  is  the  marsh  mallow,  the  roots  of  which  are  used 
principally  for  mucilage  and  for  medicinal  purposes.  Orna- 
mental representatives  are  hollyhock  (Althcea  rosea),  mallow 


5o8  BOTANY  OF  CROP  PLANTS 

(Malva    spp.),   poppy    mallow    (Callirhoe   spp.),   Abutilon 
and  Hibiscus.     The  Rose  of  Sharon  is  Hibiscus  syriacus. 

Key  to  Important  Genera  of  Malvace^ 

Stamen  column  anther-bearing  at  the  summit. 
Carpels  one-seeded. 

Involucre  of  six  to  nine  bractlets,  AUhaa  (marsh  mallow  and  holly- 
hock). 
Involucre  of  one  to  three  bractlets,  or  none. 
Petals  notched  at  the  apex,  Malva  (mallow). 
Petals  erose  at  the  apex,  Callirhoe  (poppy  mallow). 
Carpels  two-  to  several-seeded,  Abutilon. 
Stamen  column  anther-bearing  below  the  summit  (Fig.  212). 
Bractlets  of  involucre,  numerous,  Hibiscus. 
Bractlets  of  involucre,  three,  Gassy pium  (cotton). 

'      GOSSYPIUM  (Cotton) 

Habit  of  Plants,  and  Roots. — There  are  more  than  40 
species  of  Gossypium,  all  of  which  are  perennial  in  their 
native  home.  There  are  herbaceous,  shrubby,  and  tree- 
like species.  In  cultivation,  the  plants  are  annual  or  biennial, 
and  herbaceous. 

There  is  a  long,  branching,  and  deeply  penetrating  tap 
root.  This  extends  to  a  depth  of  2  feet  or  more  in  sandy  soil. 
There  are  four  rows  of  lateral  roots  from  four  shallow  grooves 
that  run  lengthwise  on  the  main  root.  The  lateral  roots  are 
only  a  few  inches  below  the  soil  surface. 

Stems. — The  main  stems  are  erect  and  branching.  The 
usual  height  of  Upland  cotton  plants  is  2}^  to  4  feet.  The 
branches  may  be  slender  or  stocky  and  are  usually  spreading. 

Kinds  of  Branches. — There  are  two  sorts  of  branches  in 
the  cotton  plant:  (i)  Vegetative  branches  or  "limbs,"  and  (2) 
fruiting  branches.  There  are  two  buds  at  the  base  of  each 
leaf.  One  of  these  is  a  true  axillary  bud,  the  other  one, 
extra-axillary.    Vegetative    branches    or    Hmbs    may    arise 


MALVACE^ 


509 


from  either  axillary  or  extra-axillary  buds.  Normal  fruit- 
ing branches  arise  only  from  extra-axillary  buds.  It  fre- 
quently happens  that  both  a  fruiting  and  a  vegetative  branch 
arise  at  one  node,  that  is,  both  the  extra-axillary  and  true 
axillary  buds  develop.  Ordinarily,  however,  only  one  bud 
at  a  node  develops.     The  axillary  buds  usually  develop  into 


Fig.  213. — Upland  cotton  (Gossypium  hirsutum).    A,  mature  boll  opened  out; 
B,  cross-section  of  young  boll;  C,  single  seed  with  fibers;  D,  young  boll. 


branches  at  only  a  few  nodes  on  the  lower  part  of  the  main 
stem.  The  accompanying  extra-laterals  remain  dormant. 
On  the  other  hand,  the  upper  true  axillary  buds  normally 
fail  to  develop,  while  each  of  their  accompanying  extra- 
laterals  forms  a  fruiting  branch.  Hence,  in  most  cultivated 
cotton  varieties,  no  fruiting  branches  occur  on  the  lower  part 
of  the  main  stem. 


5IO  BOTANY  OF  CROP  PLANTS 

In  Upland  varieties  the  fourth  or  fifth  node  is  the  first  at 
which  fruiting  branches  are  produced;  in  Egyptian  cotton, 
the  first  fruiting  branches  are  produced  from  •  the  eighth 
to  the  fourteenth  nodes. 

Vegetative  and  fruiting  branches  differ  from  each  other  in 
other  ways  than  origin.  The  former  make  a  small  angle 
with  the  stem  from  which  they  arise,  while  fruiting  branches 
are  more  horizontal.  Vegetative  branches  produce  no  flower 
buds,  while  fruiting  branches  bear  a  flower  bud  opposite  each 
leaf.  Vegetative  branches  are  frequently  as  long  as  the 
main  axis,  while  fruiting  branches  are  much  shorter.  The 
basal  internode  of  fruiting  branches  is  usually  longer  than 
the  others.  The  difference  in  length  is  much  more  pro- 
nounced in  Egyptian  cotton  than  in  Upland  cotton.  The 
internodes  of  vegetative  branches  are  about  equal  in  length. 
Vegetative  branches  may  form  both  fruiting  and  secondary 
vegetative  branches,  but  fruiting  branches  seldom  bear 
secondary  fruiting  branches  or  vegetative  branches.  Cottons 
with  short-jointed  fruiting  branches  are  more  productive  and 
usually  earlier  than  those  with  fewer  and  longer  internodes. 

Form  of  Plant. — The  general  form  of  the  cotton  plant  is 
determined  to  a  large  extent  by  the  length  and  number  of 
vegetative  branches,  as  well  as  by  the  angle  they  make  with 
the  main  axis.  The  plant  may  consist  of  a  single  stalk  with 
a  number  of  fruiting  branches  but  no  vegetative  branches. 
An  excessive  development  of  lower  vegetative  branches 
makes  a  bushy  plant. 

Branch  Zones. — The  cotton  plant  frequently  has  three 
branch  zones.  This  condition,  described  by  McLachlan,  is 
pronounced  in  Egyptian  cotton.  The  zone  of  vegetative 
branches  extends  from  the  third  to  the  tenth  node;  this  is 
followed  by  a  "transition  zone"  or  "zone  of  rudimentary 
branches,"  of  two  or  three  nodes  "at  which  the  buds  remain 


MALVACE^  511 

dormant,  or  the  branches  are  extremely  short  or  abortive." 
The  "zone  of  fruiting  branches  follows  from  about  the 
thirteenth  node  to  the  tip  of  the  plant." 

Underground  Stems. — The  cotton  plant  may  produce 
underground  stems.  These  arise  from  the  same  grooves  from 
which  lateral  roots  come.  At  first,  these  subterranean  shoots 
are  gall-like.    Later,  they  attain  various  sizes. 

Leaves. — The  leaves  have  a  regular  spiral  arrangement. 
The  most  common  phyllotaxy  in  the  cotton  plant  is  three- 
eighths.  This  is  the  normal  arrangement  in  all  pure  strains 
of  Upland  and  Sea  Island  species  and  other  natives  of  tropical 
America  that  are  related.  It  is  pointed  out  that  with  "the 
advance  of  acclimatization,  the  leaf  arrangements  are  varied 
by  frequent  examples  of  one-third  and  two-fifths  spirals" 
.  .  .  Egyptian-Upland  hybrid  plantsmay  have  a  one-third, 
two-fifths,  or  five-thirteenths  arrangement.  The  phyllo- 
taxy is  one-third  in  Asiatic  cottons.  However,  when  Asiatic 
species  are  crossed,  the  hybrid  plants  may  show  a  two-fifths 
or  three-eighths  arrangement.  Leaf  arrangement  is  similar 
on  main  stem  and  vegetative  branches,  but  on  fruiting 
branches  the  leaves  are  in  two  alternate  rows;  this  latter 
condition  is  brought  about  by  a  twisting  of  the  joints,  each 
internode  being  twisted  in  the  opposite  direction  from  the 
adjacent. 

The  leaves  are  petioled,  stipulate,  cordate  as  a  rule,  and 
three-  to  seven-lobed,  sometimes  nine-lobed.  Glands  may 
be  present  or  absent  on  the  leaves.  When  present,  they 
occur  on  the  under  side  of  the  main  ribs,  about  one-third  of 
the  distance  from  the  bases. 

The  leaves  on  fruiting  branches  are  often  irregular  in  outline 
and  may  have  one  or  two  glands.  The  leaves  on  vegetative 
branches  and  on  the  main  stem  are  regular  in  outline,  and  have 
nectaries  on  the  midrib  and  occasionally  on  the  principal 


512  BOTANY  OF  CROP  PLANTS 

veins  on  the  underside.     Three  to  six  inches  is  the  common 
length  of  Upland  cotton  leaves. 

Flowers. — Flower  buds  arise  on  fruiting  branches.  They 
do  not  arise  in  the  very  axil  of  a  leaf,  but  are  distant 
from  it.  There  is  a  flower  opposite  a  leaf  at  each  node. 
There  is  one  flower  in  each  bud.  The  flowers  of  Asiatic 
species  are  often  pendant.  Upland  cotton  flowers  are  3  to 
4  inches  across,  white  when  they  first  open  but  turning  pink 
on  the  second  day.  Sea  Island  cotton  flowers  are  usually 
yellow,  with  a  purple-red  spot  at  the  base  of  each  petal. 

Involucre. — Each  flower  is  subtended  by  an  involucre  (Fig. 
211)  composed  of  three  bracts  (sometimes  four  in  cultivation) 
united  at  the  base.  They  are  frequently  large,  dentate  or 
laciniate,  sometimes  entire.  One  of  the  bracts  is  often  some- 
what smaller  than  the  other  two  which  are  equal  in  size.  In 
some  cases  bractlets  may  occur  inside  the  involucre.  They 
alternate  with  the  bracts.  When  two  are  present  they  stand 
on  either  side  of  the  smaller  bract.  This  is  the  case  in  Upland 
varieties  in  the  United  States.  In  certain  Central  American 
varieties,  they  are  sometimes  six  bractlets,  a  pair  alternating 
with  each  of  the  three  bracts. 

Nectaries. — ^At  the  base  of  the  outer  surface  of  the  bracts 
are  nectaries,  in  American  sorts,  but  they  are  absent  in  all 
cultivated  Asiatic  cottons.  There  are  also  inner  involucral 
glands  in  both  American  and  Asiatic  varieties.  In  the 
former,  these  inner  involucral  glands  are  naked,  with  excep- 
tion of  Guatemalan  cotton,  while  in  Asiatic  cottons  they  are 
protected  by  a  velvety  covering  of  hairs. 

Calyx. — This  is  a  very  short,  cup-shaped  structure  at 
the  base  of  the  corolla.  The  rim  of  the  cup  is  usually 
five-lobed,  the  lobes  being  short  and  broad,  or  sometimes 
rather  long  and  pointed.  In  Egyptian  cotton  and  some  Asi- 
atic species,  the  rim  of  the  calyx  is  frequently  very  even, 


MALVACE^  513 

scarcely  lobed.  The  calyx  lobes  often  vary  in  size.  There 
may  be  two  large  lobes,  two  small  ones,  and  one  intermediate 
in  size.  Floral  nectaries  appear  at  the  base  of  the  calyx  on 
the  inner  side. 

" Intracalicary  Organs." — These  sometimes  occur  in  the 
cotton  flower.  They  are  a  series  of  small  greenish  organs 
between  the  calyx  and  corolla.  There  are  five  of  these 
structures,  but  often  some  of  them  are  so  small  as  to  be  visible 
only  by  use  of  the  hand  lens.  They  are  attached  to  the 
calyx,  and  alternate  with  its  lobes.  Cook  and  Meade  regard 
them  as  "supernumerary  calyx  lobes  or  as  representing  free 
stipular  elements  of  the  calyx  lobes." 

Corolla. — This  is  hypogynous.  There  are  five  petals,  often 
united  at  the  base,  and  attached  to  the  lower  part  of  the 
stamen  tube.  They  are  usually  yellow  or  red  in  color.  In 
G.  harhadense  the  petals  are  yellow  or  sulphur-colored,  with  a 
purple  spot  on  the  claw.  The  petals  are  convolute  in  the 
bud. 

Stamens. — These  are  monodelphous  in  cotton.  There  are 
often  as  many  as  80  or  90  stamens,  all  inserted  on  a  tubular 
staminal  column,  which  encloses  the  pistil.  The  column  is 
dilated  at  the  base  and  narrowed  above.  There  are  five 
vertical  ridges  on  the  staminal  column,  each  of  which  gives 
rise  to  a  number  of  filaments.  The  column  is  regarded  as 
being  made  up  of  the  united  filaments  of  the  stamens.  The 
filaments  are  thread-like  and  exserted.  The  anthers  are  one- 
celled,  and  each  is  dehiscent  into  two  halves,  by  a  semicircular 
opening. 

Ovary  (Fig.  213). — This  has  three  to  five  cells  or  "locks." 
As  a  rule,  the  style  is  long,  thus  bringing  the  stigmas  above 
the  stamens.  In  Upland  varieties,  however,  the  style  is 
usually  shorter  than  the  stamens.  There  are  as  many 
stigmas  as  there  are  cells  in  the  ovary. 
33 


514  BOTANY  OF  CROP  PLANTS 

Pollination,  Fertilization,  and  Development  of  Fruit. — 

Both  cross-  and  self-fertilization  may  occur  in  cotton.  Bees 
may  be  necessary  in  those  varieties  in  which  the  style  is  long 
and  brings  the  stigmas  above  the  anthers.  Floral  nectaries, 
at  the  base  of  the  calyx  on  the  inner  side,  are  reached  from 
within  the  corolla  by  long-tongued  bees  and  butterflies. 
This  is  enabled  by  the  failure  of  the  petals  to  overlap  at 
the  base,  thus  leaving  gaps  through  which  the  insect  may 
protrude  its  tongue. 

In  Mississippi  the  period  required  for  maturity  of  bolls  is 
from  forty-four  to  forty-six  days. 

The  seeds  retain  their  attachment  to  the  placenta  until  lint 
begins  to  develop,  when  their  connection  is  broken  through 
the  absorption  of  the  seed  stalk,  and  the  mechanical  pressure 
of  growing  lint.  Hence,  the  seeds  come  to  occupy  a  position 
in  the  center  of  the  cavity.  Fiber  begins  to  develop  first  at 
the  apex  of  the  seed. 

Fruit. — The  cotton  fruit  (Fig.  213)  is  a  leathery  capsule 
loculicidally  dehiscent  by  three  to  five  valves.  The  mature 
capsule  is  called  a  "boll."  It  varies  in  shape:  subglobose, 
oval,  or  ovate-acuminate.  The  number  of  cells  or  "locks" 
is  three  or  four  in  Sea  Island  and  Egyptian  varieties,  and  four 
or  five  in  Upland  sorts. 

Seeds. — There  are  numerous  seeds  in  each  "boll."  Seeds 
vary  in  shape:  subglobose,  ovate,  or  subovate. 

Fiber. — The  cotton  fiber  or  hair  is  a  simple  extension  of  an 
epidermal  cell  of  the  seed  coat.  As  a  rule,  there  are  two  kinds 
of  hairs  on  the  seed:  (i)  long  hairs — lint  or  commercial 
fiber  "(staple)"  and  (2)  short  hairs  or  fuzz.  The  fuzz  may 
be  white,  green,  or  brown  in  color.  Some  varieties  produce 
no  fuzz;  hence  when  the  seed  is  "ginned,"  it  is  left  naked. 
Fuzzy-seeded  varieties  usually  possess  an  abundance  of  long 
fibers.     A  high  percentage  of  lint  usually  indicates  small 


MALVACE^  515 

seed.  In  some  varieties,  the  lint  may  form  34  per  cent,  or 
more  of  the  seed. 

Distribution  of  Seed  Hairs. — ^Lint  and  fuzz  are  mixed  to- 
gether over  the  entire  seed  surface  in  Upland  cottons.  In 
Egyptian  sorts,  fuzz  is  limited  to  the  ends  of  the  seeds,  with 
long  fibers  between  thet\YO  patches.  The  lint  at  the  tip  of 
the  seed  in  some  Upland  cottons  is  longer  than  that  at  the 
base. 

Fiber  Differences. — The  fibers  of  Upland  cotton  are  i  to  2 
centimeters  long,  and  abundant;  those  of  Sea  Island  are  2.5 
to  4  centimeters  long,  but  the  yield  is  not  as  great  as  in  the 
preceding  species. 

The  following  table  is  taken  from  Monie: 

Average  length  of     Average  diameter 
staple  in  inches       of  staple  in  inches 

Sea  Island 1.61  o. 000640 

New  Orleans 1.02  0.000775 

Texas i .  00  o .  000763 

Upland 0.93  0.000763 

Egyptian 1.41  0.000655 

Form  and  Structure  of  Fiber. -^Yoxxng  cotton  fibers  are 
circular  in  cross-section.  As  they  increase  in  length,  the 
walls  become  thinner,  and  the  fiber  takes  on  a  flattened  rib- 
bon-like appearance.  The  thickness  of  the  walls  becomes 
greater  when  the  boll  opens,  due  to  the  rapid  consolidation 
of  the  liquid  cell  contents,  which  become  deposited  on  the 
inner  walls.  The  deposition  is  irregular,  hence  the  twisting 
of  the  fiber.  This  twisting  is  a  characteristic  of  the  cotton 
fiber.  The  twist  is  not  necessarily  in  one  direction  through- 
out its  length;  there  may  be  a  reversal  here  and  there. 

The  fiber  is  uniform  in  diameter  for  about  three-fourths 
of  its  length,  and  then  tapers  gradually  to  a  point.  At  the 
point,  it  may  be  perfectly  cylindrical  and  solid.  The  hair 
cavity  or  lumen  takes  up  about  two-thirds   of   the   entire 


5l6  BOTANY  OF  CROP  PLANTS 

breadth.  Immature  fibers  or  unripe  fibers  may  show  no 
evidence  of  internal  structure,  but  are  smooth,  straight,  and 
flat.  "Kempy"  fibers  or  "dead  cotton"  are  such  that  are 
normal  in  structure  a  portion  of  their  length,  and  have  the 
appearance  of  immature  and  overripe  fibers  for  another 
portion.  The  quality  of  fiber  depends  largely  upon  the 
number  and  regularity  of  twists,  and  upon  its  length  and 
fineness.     The  mature  cotton  fiber  is  almost  pure  cellulose. 

Cotton  Fibers  Distinguished  from  Other  Common  Textile  Fibers. — There 
are  two  chief  ways  of  distinguishing  textile  fibers,  by  microscopical  examina- 
tion and  by  chemical  reactions.  The  cotton  fiber  is  a  flat,  ribbon-like  band 
twisted  in  a  characteristic  manner.  The  flax  fiber  is  a  straight,  untwisted, 
cylindrical  fiber,  with  peculiar  transverse  markings  at  intervals  along  its 
length.  Hemp  fibers  resemble  those  of  flax,  but  they  may  be  distinguished 
from  the  latter  by  the  peculiar  forked  ends  which  are  nearly  always  exhibited, 
whereas  flax  fibers  never  show  this  character.  All  wool  fibers  possess  char- 
acteristic overlapping  scales.  The  silk  fiber  is  smooth,  structureless,  trans- 
parent and  quite  regular  in  diameter. 

There  are  many  ways  of  distinguishing  the  fibers  by  observing  their  reac- 
tions to  various  chemicals.     The  following  short  key  will  illustrate  a  few  of 
their  characteristic  reactions. 
Dissolves  in  caustic  potash. 

An  alkali  solution  of  the  fiber  treated  with  lead  acetate  colors  fiber 

black.  Wool. 
The  above  treatment  does  not  color  the  fiber.  Silk. 
Does  not  dissolve  in  caustic  potash. 

With  iodine  and  sulphuric  acid  the  fiber  swells  and  becomes  green, 


With  iodine  and  sulphuric  acid  the  fiber  swells  and  becomes  blue. 

Immerse  fiber  in  concentrated  sulphuric  acid  for  two  minutes,  wash 
in  water,  treat  with  dilute  ammonia,  dry — fiber  forms  a  gelatinous 
mass  soluble  in  water,  Cotton. 
With  above  treatment,  fiber  is  not  altered,  Linen. 
Species. — Watt,  in  his  great  work,  describes  42  distinct  species  and  varie- 
ties of  Gossypium.     A  number  of  them  are  known  only  in  the  wild  state. 
Gossypium,  as  a  genus,  is  indigenous  to  tropical  regions.     It  is  now  grown 
under  cultivation  to  the  40°  latitude  on  either  side  of  the  equator. 

Watt  divides  the  wild  and  cultivated  cotton  plants  of  the  world  into  five 
"sections,"  as  follows: 


MALVACE^  517 

Section  I.  Species  with  a  Fuzz  hut  no  Floss. — "Wild  species  (never  recorded 
as  met  with  under  cultivation),  distributed  from  the  western  coast  tracts  and 
islands  of  America  to  Australia."  Here  are  included  G.  sturtii,  davidsonii, 
klotzschianum,  robinsoni,  darwinii,  tomentosum,  drynarioides,  harknessii,  and 
stocksii.  The  bracteoles  are  free,  extrafloral  nectaries  absent,  the  fruit  small, 
and  the  rather  large  seeds  have  a  fuzz  but  no  lint. 

Section  II.  Fuzzy-seeded  Cottons  with  United  Bracteoles. — "One  or  perhaps 
two  members  of  this  section  have  been  recorded  as  met  with  in  a  wild  condi- 
tion, the  others  are  undoubted  cultivated  plants  derived  very  possibly  from 
four  specific  types — G.  arboreum,  G.  nanking,  G.  obtusifolium,  and  G.  herba- 
ceum."  Most  of  these  are  Asiatic  and  African  cottons.  The  bracteoles  are 
united  below,  the  claws  of  the  petals  are  purple,  and  the  seeds  are  covered 
with  both  fuzz  and  lint.  Watt  is  strongly  of  the  opinion  that  G.  arboreum  var. 
neglecta,  was  at  an  early  date  introduced  into  the  United  States,  the  form  being 
known  as  "Okra."     Its  cultivation  was  abandoned,  however. 

G.  nanking  is  the  "Chinese  cotton"  of  commerce,  also  known  as  "Siam 
cotton"  or  "Nankin  cotton."  It  is  "cultivated  in  China,  Japan,  the  Malaya, 
Siam,  Burma,  India,  the  northwest  Himalaya,  Persia,  Central  Asia,  to  the 
Celebes;  less  abundantly  in  Madagascar,  Arabia,  and  Africa." 

G.  obtusifolium  is  an  oriental  species  that  occurs  both  wild  and  cultivated 
in  India  and  Africa.     Var.  wightiana  is  the  most  valuable  Indian  cotton. 

G.  herbaceum  is  not  known  to  occur  as  a  wild  species  anywhere,  although 
Watt  is  of  the  opinion  that  it  is  indigenous  to  North  Arabia  and  Asia  Minor. 
In  1621,  it  was  brought  to  the  United  States,  and  for  a  time  cultivated,  but 
was  finally  replaced  by  the  more  desirable  West  Indian  cottons.  G.  herbaceum 
is  considered  to  be  the  first  cotton  cultivated  in  Europe.  Watt  believes  that 
it  still  survives  as  an  Upland  cotton  of  the  United  States,  though  "mostly  in 
a  state  of  hybridization  with  G.  hirsutum."  Cook  regards  our  Upland  cot- 
tons as  belonging  to  G.  hirsutum. 

Section  III.  Fuzzy-seeded  Cottons  with  Free  Bracteoles. — These  are  Ameri- 
can and,  in  one  case,  African  species.  Here  belong  G.  muslelinum,  punctatum, 
hirsutum,  palmerii,  fruticulosum,  schottii,  lanceolatum,  microcarpum,  pertivi- 
anum,  and  mexicanum.  G.  mustelinum  is  a  native  of  Brazil  and  Colombia. 
G.  punctatum  is  native  to  southern  United  States,  West  Indies,  and  northern 
Africa.  It  exists  in  a  state  of  cultivation  in  various  sections.  Watt  considers 
G.  hirsutum  as  "only  a  cultivated  state  of  G.  punctatum"  ...  In  this 
country,  however,  the  Upland  cottons  are  all  considered  as  offsprings  of 
hirsutum  (Fig.  214).  G.  palmerii,  fruticulosum  and  lanceolatum  are  Mexican 
species.  G.  schottii  is  from  Yucatan,  and  is  known  as  the  "split-leaved"  cot- 
ton. G.  microcarpum,  known  as  Ashmouni  cotton  and  Red  Peruvian  cotton, 
grows  in  Mexico,  northern  South  America,  Africa,  and  Malaya.  It  is  culti- 
vated. G.  peruvianum  is  the  Peruvian  or  Andes  cotton.  Watt  regards  many 
of  the  Egyptian  cottons  as  races  or  hybrids  of  this  species.    G.  mexicanum 


Si8 


BOTANY  OF  CROP  PLANTS 


probably  originally  came  from  Mexico.  Watt  says:  "I  am  convinced  that 
the  best  Upland  cottons  would  be  more  correctly  described  as  cultivated  states 
of  this  plant  (G.  mexicanum) ,  rather  than  as  forms  of  G.  hirsutum."  He  con- 
siders many  of  our  Upland  or  short  staple  cottons  as  hybrids  of  G.  mexicanum 
and  G.  hirsutum,  sometimes  with  the  characters  of  the  one  predominating, 
sometimes  with  those  of  thejother.     The  long  staple  Upland  series,  chief 


Fig.  214. — American  upland  cotton  (Gossypium  hirsutum).     (After  Watt.) 


representatives  of  which  are  Allen,  Peeler,  Simms  and  Sunflower,  are  also 
hybrids,  with  hirsutttm  characters  dominant. 

Section  IV.  Naked-seeded  Cottons  with  the  Bracteoles  Free  or  Nearly  so  and 
Glands  Conspicuous. — This  section  includes  both  Old-  and  New-World  forms. 
The  seeds  are  naked  or  nearly  so,  and  the  lint  is  easily  removed.  There  is 
always  some  fuzz  on  the  seed  at  the  apex,  hence  they  are  not  absolutely 


MALVACE^ 


519 


naked."  To  this  section  belong  G.  tailense,  purpurasccns,  vilijolimn,  har- 
badense,  and  brasiliense. 

G.  taitense  is  the  wild  cotton  of  Polynesia.  It  is  not  cultivated.  G.  pur- 
purascens  is  known  as  Bourbon,  Porto  Rico,  and  Siam  cotton.  It  is  an  im- 
portant cultivated  species.     G.  vitifoUum,  the  vine-leaved  cotton,  has  fur- 


FiG.  215. — Sea    Island    cotton     (Gossypium    barbadense).     (After     Wait.) 

nished  a  number  of  valuable  cultivated  types  in  Egypt,  Antilles,  etc.  It  is 
closdy  related  to  G.  barbadense.  G.  barbadense  (Fig.  215)  includes  the  Sea 
Island  cottons  of  America  and  Egypt.  Watt  believes  that  Sea  Island  cotton 
is  a  modern  development,  not  indigenous  to  Barbados  or  any  of  the  West 
Indian  Islands,  but  probably  from  somewhere  in  South  America.  ^ He  says 


520  BOTANY  OF  CROP  PLANTS 

that  "it  is  highly  probable  the  modern  stock  is  a  hybrid."  The  Sea  Island 
cottons  proper  which  have  been  grown  with  the  greatest  success  on  the  islands 
off  the  coast  of  Carolina  and  Georgia  are  referred  to  G.  barbadense  var. 
maritima.  G.  brasiliense  is  indigenous  to  South  America.  It  is  cultivated 
extensively  and  is  known  as  "  Chain,  Kidney,  Stone,  Brazilian,  Guiana,  Esse- 
quibo,  Berbiche,  Bahia,  Pernambuco,  and  Coton-pierre  cottons."  This  group 
is  no  longer  of  great  commercial  importance. 

Section  V.  Naked-seeded  Cotton  with  Bracteoles  quite  Free  and  Floral  Glands 
Absent. — Only  one  species,  G.  kirkii,  belongs  to  this.  It  is  from  East  and 
Central  Africa,  and  is  not  cultivated.     The  lint  is  easily  removed  from  the 


Wild  Cottons. — Wild  cottons  all  have  a  red-colored,  hairy 
coating  on  the  testa.  As  is  seen  above,  there  may  be  fuzz 
only,  or  both  fuzz  and  lint,  or  lint  alone.  Cultivated  cottons 
have  a  long  white  lint,  in  both  fuzzy-seeded  and  naked-seeded 
forms.  Sea  Island  cottons  have  the  least  fuzz  of  all  culti- 
vated forms.  White  lint  may  be  regarded  as  brought  about 
by  cultivation.  The  appearance  of  rust-colored  fuzz  or 
lint  may  be  regarded  as  a  tendency  to  revert  to  the  ancestral 
type. 

The  reddish  tint  of  wild  cottons  is  due  to  an  aggregation  of 
colored  particles  in  the  central  core  of  the  fiber. 

American  Cottons. — American  authorities  place  the  cot- 
tons of  the  United  States  into  two  species:  G.  hirsutum, 
American  Upland  cotton,  and  G.  barbadense,  Sea  Island, 
cotton.  It  has  been  noted  above,  however,  that  Watt  claims 
that  our  Upland  cottons  are  hybrids  between  G.  hirsutum 
and  G.  mexicanum.  Ninety-nine  per  cent,  of  the  cotton 
crop  in  the  United  States  is  Upland. 

The  most  important  distinction  between  these  two  species 
is  in  staple  length.  The  fibers  of  Upland  cotton  are  from  i 
to  2  centimeters  long,  those  of  Sea  Island  2.5  to  4  centimeters 
long.  The  yield  of  the  former  is  greater  but  the  quality  not 
so  fine.  The  flowersare  white,  turning  red  on  the  second  day 
of  blooming  in  Upland  cotton,  but  yellow  with  a  purple-red 


MALVACE^  521 

spot  at  the  base  of  each  petal  in  Sea  Island  cotton.  The 
latter  is  limited  to  a  small  area  along  the  coast  of  South 
CaroHna,  Georgia,  and  Florida. 

Tjrpes  and  Varieties. — Upland  is  the  chief  American  cotton.  It  has  been 
divided  by  Duggar  into  a  number  of  "groups"  as  follows: 

1.  Big  Boll  Group. — Plants  vigorous  and  stocky;  limbs  strong,  usually  two 
in  number;  fruiting  branches  strong,  varying  from  short  to  long;  bolls  large, 
45  to  68  of  them  yielding  a  pound  of  cotton;  four  to  five  locules;  seeds  large, 
very  fuzzy,  white  to  brownish  gray  or  greenish  in  color;  lint  20  to  30  milli- 
meters long.  Examples:  Russell,  Truitt,  Truimple,  Texas  Storm-proof,  and 
Jones  Improved. 

2.  Long  Staple  Group. — Plants  slender;  limbs  two  or  three,  sometimes  ab- 
sent, slender;  fruiting  branches  also  slender;  bolls  small  to  medium,  long, 
slender,  tapering  to  a  point,  three-,  four-,  or  five-loculed;  seeds  medium  to 
large,  sometimes  partly  naked,  but  usually  densely  covered  with  a  brownish- 
gray  fuzz;  lint  30  to  45  millimeters  long,  percentage  low.  Examples:  Allen, 
Griffin,  and  Cook. 

3.  Cluster  Group. — Plants  slender,  often  tall,  limbs  heavy,  one  to  several; 
fruiting  branches  very  short-jointed,  causing  the  bolls  and  leaves  to  be  in 
clusters,  apparently  two  or  three  from  each  node;  bolls  small  to  medium, 
four-  to  five-loculed;  seeds  small  to  medium,  fuzzy,  gray  to  brownish-  or 
greenish  gray;,  lint  short,  soft,  and  of  good  strength.  Examples:  Jackson, 
Dickson. 

4.  Semi-cluster  Group. — This  group  resembles  closely  the  preceding.  The 
bolls  are  borne  singly  but  close  together.  It  is  probably  a  hybrid  group  with 
strong  cluster  tendencies.  Examples:  Peerless,  Defiance,  Bernett,  Berryhill, 
Hawkins. 

5.  Rio  Grande  or  Peterkin  Group. — Plants  slender;  limbs  one  to  several; 
fruiting  branches  slender,  long-jointed;  bolls  very  small  to  medium,  three-, 
four-,  or  five-loculed;  seeds  very  small  to  medium,  nearly  smooth,  dark- 
colored,  sometimes  covered  with  a  short  fuzz;  lint  medium  in  length,  percent- 
age large.     Examples:  Peterkin,  Texas  Wood,  Rio  Grande. 

6.  King  or  Early  Group. — Plants  small  and  slender;  limbs  one  to  three  or 
more;  fruiting  branches  medium  to  short-jointed,  but  long  in  proportion  to 
plant  height;  bolls  small,  three-,  four-,  or  five-locked;  seeds  small  to  medium, 
fuzzy,  greenish  or  brownish  gray;  lint  short  to  medium,  t,^  to  35  per  cent,  of 
seed.     Earliest  American  cottons.     Examples:  King,  Dozier,  Hodge,  Mascot. 

7.  Long-limbed  Group. — Plants  large;  limbs  long  with  long  joints;  bolls  and 
seeds  medium  to  large;  lint  percentage  low;  fuzz  of  various  shades.  Exam- 
ples: Petit  Gulf,  Peeler,  Hagaman.     This  group  is  of  little  importance.  . 

8.  Intermediate  Group. — This  group  includes  a  number  of  varieties  with 


522  BOTANY  OF  CROP  PLANTS 

characters  so  badly  mixed  up  as  to  make  it  impossible  to  refer  them  to  any 
particular  group.  It  is  well  known  that  our  American  cottons  hybridize  quite 
readily  under  field  conditions.  .  Examples:  Breeden,  Boyd,  Roby,  Tucker. 

Environmental  Relations. — Cotton  is  a  tropical  plant. 
The  upper  latitudinal  limit  of  cotton  growing  in  this  country 
is  about  coextensive  with  the  summer  (June,  July  and  Au- 
gust) isotherm  77°F.  The  plant  is  extremely  sensitive  to  low 
temperatures,  and  even  a  light  frost  in  the  fall  stops  its 
development.  It  seldom  matures  in  less  than  i8o  days. 
The  plant  not  only  requires  a  high  temperature,  but  also 
one  not  subject  to  fluctuations,  as  such  conditions  cause 
premature  ripening.  After  the  plant  has  attained  its  vege- 
tative growth,  the  ripening  of  fruits  and  seeds  is  favored  by 
cooler  nights  than  prevailed  up  to  that  period. 

Light,  frequent  showers  which  permit  of  an  abundance  of 
sunshine  favor  the  development  of  the  plant.  Too  much 
rain  is  liable  to  stimulate  an  excessive  development  of  vege- 
tative growth  at  the  expense  of  fruit  formation. 

Upland  cottons  are  adapted  to  a  variety  of  soils,  while  the 
Sea  Island  varieties  are  best  suited  to  soils  with  low  water- 
retaining  capacity,  and  of  medium  fertility. 

Picking  and  Ginning  of  Cotton.— Cotton  is  picked  by 
hand,  and  loaded  into  wagons.  This  labor  is  performed 
almost  exclusively  by  negroes.  The  seed  cotton  is  removed 
from  the  wagon  by  means  of  a  suction  fan,  and  carried  over 
a  single  gin  or  battery  of  gins.  It  passes  into  chutes  over  the 
feeders,  and  is  then  fed  evenly  to  the  gin  saws,  where  the  lint 
and  seed  are  separated.  The^seeds  are  carried  by  a  screw 
conveyor  to  the  seed  house  or  seed  bin.  The  lint  cotton  is  led 
from  the  gin  saws  through  a  flue  to  the  condenser.  Here  it  is 
cleaned,  smoothed  out  into  sheets  or  bats,  wrapped  and  tied 
into  bales.  The  usual  size  of  a  cotton  bale  is  27  by  54  inches 
and'the  weight  about  500  pounds.    Sea  Island  cotton  is  ginned 


MALVACE^  523 

in  a  type  known  as  the  roller  gin,  as  the  fiber  is  injured  by  the 
saw  gin  type. 

When  seed  cotton  comes  to  the  gin,  it  contains  boll  hulls 
and  trash.  This  is  usually  removed  by  passing  the  seed 
cotton  through  a  cleaner,  before  it  reaches  the  gin  saws. 
The  boll  hulls  are  frequently  used  for  fuel. 

Bleaching  of  Cotton. — The  object  of  this  process  is  to 
remove  the  waxy  coating  of  the  fiber,  in  order  that  it  may 
absorb  the  dyestuffs  easily,  and  also  remove  all  the  impurities 
adhering  to  the  fiber.  Cotton  may  be  bleached  in  any  stage 
of  its  manufacture,  in  the  loose  state,  as  yarn,  or  as  cloth. 
The  process  of  bleaching  is  the  most  thorough  and  is  carried 
further  in  the  making  of  print  cloth  than  in  the  preparation 
of  other  grades  of  cloth,  as  the  cloth  must  be  absolutely  white 
and  free  of  all  impurities  in  order  that  the  printing  colors 
can  be  applied  properly,  and  the  patterns  appear  distinct 
and  sharp.  The  cloth  is  first  singed  to  remove  loose  fibers 
and  lint,  and  leave  a  clear  even  surface.  It  is  then  taken 
through  the  boiling  out  process,  in  which  the  cloth  is  given 
one  or  more  boilings  in  caustic  soda  in  order  to  remove  the 
waxy,  fatty  and  pectic  substances  from  the  fiber.  After  a 
thorough  washing  in  water,  the  cloth  is  treated  with  a 
bleaching  powder  solution.  The  souring  process  follows, 
in  which  the  cloth  by  treatment  with  a  dilute  solution  of 
sulphuric  acid  is  rendered  free  of  the  lime  compounds  and 
undecomposed  chlorine  derivatives.  Another  thorough 
washing  then  follows,  after  which  the  cloth  is  given  a  finish, 
the  nature  of  which  depends  upon  the  use  to  which  it  will 
be  put. 

Uses  of  Cotton.— The  lint  is  spun  into  thread  or  yarn,  arid 
woven  into  all  sorts  of  fabrics.  The  finer  threads  are  made 
from  Sea  Island  cotton,  while  ordinary  threads  and  yarns 
are  from  long  staple  upland  cotton.     The  short  lint  or  fuzz. 


524  BOTANY  OF  CROP  PLANTS 

known  as  "linters,"  which  is  not  removed  in  ginning,  is 
taken  from  the  seeds  and  made  into  coarse  twine,  carpets, 
and  batting. 

Cottonseed  Hulls. — These  are  used  in  the  manufacture  of 
paper  and  fiber  board  from  which  are  made  gear  wheels, 
trunks,  etc.  The  hulls  are  also  utihzed  as  fuel  and  fertilizer, 
and  as  a  cattle  food. 

Cottonseed  Oil. — This  is  one  of  the  most  valuable  products 
of  the  cotton  plant.  The  oil  of  the  seed  is  in  the  embryo. 
After  the  seed  coats  are  removed,  the  embryos  ("meats"), 
are  cooked  for  twenty  to  thirty  minutes  to  melt  the  oil,  and 
to  drive  off  some  of  the  water.  The  oil  is  then  extracted 
under  pressure.  A  ton  of  seed  yields  about  40  gallons  of 
crude  oil.  Various  grades  of  cottonseed  oil  are  secured  by 
different  processes  of  refining  and  filtering. 

Cottonseed  oil  is  now  produced  in  large  quantities  in  this 
country.  The  United  States  exported  35,304,000  gallons 
of  the  oil  in  1 9 13.  It  is  used  for  edible  purposes,  appearing 
on  the  market  usually  under  some  such  name  as  "sweet  nut 
oil,"  "salad  oil,"  or  "table  oil."  It  may  be  utilized  as  an 
adulterant  of  such  oils  as  peanut  and  olive  oils.  However, 
it  is  fully  as  nutritive  as  olive  oil  and  is  actually  preferred 
by  many.  It  is  used  sometimes  in  the  manufacture  of  soaps. 
It  is  also  extensively  employed  in  the  manufacture  of  "oleo- 
margarine," and  butter  and  lard  substitutes.  "Cottolene" 
is  composed  of  refined  cottonseed  oil  and  beef  suet. 

Cottonseed  Meal.— Cottonseed  meal  is  the  ground  cake 
left  after  the  oil  is  pressed  from  cotton  seed.  It  is  now  used 
extensively  as  a  feed,  although  formerly  it  was  considered 
of  little  value.  United  States  produces  annually  about 
2,000,000  tons  of  cottonseed  meal,  valued  at  about  $53,000,- 
000.  The  death  of  animals  sometimes  associated  with  its 
use   is   due   to   a   toxic    substance,    gossypol.     Cottonseed 


MALVACEAE 


525 


kernels  are  now  rendered  less  toxic  by  extracting  the  gossypol 
with  ether,  or  with  ether  and  alcohol;  or  by  treating  the  meal 
with  an  alcoholic  solution  of  an  alkah,  thus  oxidizing  the 


t3  J« 


-Si     !» 

t-1 


oj  a. 


o  -o 

u      . 
O    2^2 

Y  •?  -o 


gossypol  and  rendering  it  non-toxic.     Cottonseed  meal  is 
also  highly  prized  as  a  fertilizer. 
Guncotton.— This  is  a  powerful  explosive  made  by  treating 


526 


BOTANY  OF  CROP  PLANTS 


cotton  or  some  other  form  of  cellulose  with  nitric  acid  or 
sulphuric  acid.  Military  guncotton  is  a  mixture  of  very 
highly  nitrated  cellulose  nitrates.  Less  highly  nitrated 
guncotton  is  soluble  in  alcohol  and  ether,  and  such  soluble 
guncotton  is  used  in  the  manufacture  of  collodion,  celluloid, 
etc.  Celluloid  is  made  by  subjecting  a  mixture  of  guncotton, 
camphor,  and  other  minor  substances  to  great  pressure. 
Collodion  is  a  solution  of  guncotton  in  ether  and  alcohol. 


Fig.  2  17. — Cotton-producing  regions  of  the  United  States.  (From 
Essentials  of  Geography,'  Second  Book.  Copyright,  1916,  by  Albert  Perry 
Brigham  and  Charles  T.  McFarlane.     American  Book  Company,  Publishers.) 

Importance,  and  Production  of  Cotton. — Cotton  is  the 
most  important  fiber  plant  in  the  world.  The  clothing  of  a 
great  majority  of  people  is  cotton.  The  largest  of  manufac- 
turing enterprises  are  concerned  with  the  production  of  cotton 
goods.  Cotton  is  the  most  important  article  of  world  trade. 
The  world's  crop  in  1910  is  estimated  at  22,433,269  bales,  as 
compared  with  15,893,591  bales  in  1900.     In  1914,  the  United 


MALVACE^  527 

States  led  in  cotton  production,  with  16,134,930  bales. 
British  India  ranked  second  with  an  output  of  4,238,494 
bales.  The  following  table  gives  the  production  of  cotton 
by  States,  1915. 

Production  of  Lint  (Excluding  Linteks)  ik  soo-pound  Gross  Weight 
Bales,  by  States,  iqis 

State  Bales 

Texas 3,175,000 

Georgia 1,900,000 

South  Carolina 1,160,000 

Alabama 1,050,000 

Mississippi 940,000 

Arkansas. . .". 785,000 

North  Carolina 708,000 

Oklahoma 630,000 

Louisiana 360,000 

Tennessee 396,000 

All  other  States •. 108,000 

United  States 11,161,000 

Total  value  of  crop $602,393,000 

HIBISCUS  ESCULENTUS  (Okra,  Gumbo) 

Description.— Okra  or  gumbo  is  a  stout,  annual  plant. 
The  stems  are  cylindricaljand  usually  rough-hairy.  The 
leaves  are  large,  heart-shaped,  three-  to  five-lobed,  and  with 
very  prominent  veins;  the  lobes  are  coarsely  toothed.  The 
solitary,  showy  flowers  arise  in  the  leaf  axils;  they  are 
subtended  by  numerous,  narrow,  involucral  bracts;  the 
calyx  is  five-cleft;  there  are  five  large  yellow  petals;  the 
stamens  form  a  column  which  is  five-toothed  at  the  apex,  and 
is  anther-bearing  along  its  entire  length;  the  ovary  has  five 
cells,  each  of  which  has  several  ovules;  there  are  five  style 
branches,  each  tipped  by  a  capitate  stigma.  Okra  is  regu- 
larly cross-pollinated  by  insects,  chiefly  bumblebees.  The 
fruit  is  a  pod  with  five  longitudinal  ribs;  the  seeds  are  large 
and  kidney-shaped. 


528  BOTANY  OF  CROP  PLANTS 

Geographical. — The  original  home  of  okra  is  Africa.  It  is  now  introduced 
into  many  civilized  countries,  and  grown  as  a  vegetable  with  particular  suc- 
cess in  the  warmer  ones. 

Types.— Beattie  divides  the  varieties  of  okra  into  three 
types:  (i)  Tall  green,  (2)  dwarf  green,  and  (3)  lady  finger. 
Each  of  these  is  further  divided  into  long-podded  and  short- 
podded  sorts.  Plants  of  the  "lady-finger"  type  are  much 
Hghter  in  color  than  those  of  the  other  two  types.  Tall 
green  okras  are  4  to  8  feet  high,  dwarf  green  sorts  about  i}4, 
to  2>}"2  feet  high,  and  lady-finger  varieties  close  to  3  feet  high. 

Uses. — Okra  is  used  chiefly  in  soups.  Not  infrequently 
the  young  seeds  are  cooked.  When  the  pods  are  very  young 
and  tender,  they  are  cooked  and  served  as  a  salad.  A  fiber 
used  in  the  manufacture  of  paper  is  sometimes  made  from 
both  stems  and  mature  pods.  In  some  countries  the  pods 
are  dried,  and  in  this  form  kept  for  winter  use. 

References 

Balls,  W.  L.  :  The  Sexuality  of  Cotton.     Yearbook  Khediv.  Agr.  Soc.  Cairo, 

1905. 
Beattie,  W.  R.:  Okra:  Its  Culture  and  Uses.     U.  S.  Dept.  Agr.  Farmers' 

Bull.  232:  1-16,  1905. 
Bowman,  F.  H.:  Structure  of  the  Cotton  Fiber.     Manchester,  England,  1881. 
Brooks,  E.C.:  The  Story  of  Cotton.     Chicago,  New  York,  and  London,  1911. 
Cook,  O.  F.,  and  Meade,  R.  M.:  Arrangement  of  Parts  in  the  Cotton  Plant. 

U.  S.  Dept.  Agr.  Bur.  Plant  Ind.  Bull.  222:  1-26,  1911. 
Dimorphic  Leaves  of  Cotton  and  Allied  Plants  in  Relation  to  Heredity. 

U.  S.  Dept.  Agr.  Bur.  Plant  Ind.  Bull.  221:  1-59,  191 1. 
Cook,  O.  F.,  McLachlan,  Argyle,  and  Meade,  R.  M.:  A  Study  of  Diversity 

in  Egyptian  Cotton.     U.  S.  Dept.  Agr.  Bur.  Plant  Ind.  Bull.  156:  1-60, 

1909- 
DuGGAR,  J.  F.:  Descriptions  and   Classification   of  Varieties  of  American 

Upland  Cotton.     Ala.  Agr.  Exp.  Sta.  Bull.  140:  1-104,  1907. 
Evans,  W.  H.:  Botany  of  Cotton.     U.  S.  Dept.  Agr.  Office  of  Expt.  Stats. 

Bull.  33:  67-80,  1896.     Contains  a  Bibliography  of  Cotton. 
Flatters,  A.:  The  Cotton  Plant:  Its  Development  and  Structure  and  the 

Evolution  and  Structure  of  the  Cotton  Fiber.    London  and  Manchester. 

1906. 


MALVACE^  529 

Heizmann,  H.:  Die  Baumwolle.     Zurich  und  Leipsic,  1913. 

Meade,  R.  M.  :  Methods  of  Securing  Self-pollination  in  Cotton.     U.  S.  Dept . 

Agr.  Bur.  Plant  Ind.  Cir.  121:  29:  30,  1913. 
MoNiE,   Hugh:  The  Cotton  Fiber,   Its  Structure,   Etc.     Manchester  and 

London,  1890. 
Oppel,  a.:  Die  Baumwolle.    Leipsic:  Duncker  und  Humblot,  1902. 
Parlatore,  Filippo:  Le  specie  dei  cotoni,  1866. 

Reed,  E.  L.:  Leaf  nectaries  of  gossypium.     Bot.  Gaz.,  63:  229-231,  1917. 
Steuckart,  C:  Die  Baumwolle,  ihre  Herkunft,  ihre  Verwendung,  ihre  Ge- 

schichte,  und  Bedeutung.    Leipsic,  1914. 
Tyler,  F.  J. :  The  Nectaries  of  Cotton.     U.  S.  Dept.  Agr.  Bur.  Plant  Ind. 

Bull.  131:45-54,  1908. 
Varieties  of  American  Upland  Cotton.     U.  S.  Dept.  Agr.  Bur.  Plant  Ind. 

Bui.  163:  1-127,  1910. 
Watt,  G.:  The  Wild  and  Cultivated  Cotton  Plants  of  the  World.     New 

York  and  London,  1907. 


34 


CHAPTER  XXXIV 
UMBELLIFER^  (Carrot  Family) 

Stems  and  Leaves. — All  the  common  representatives  of 
the  carrot  family  are  herbs.  A  very  few  are  shrubs  or  trees. 
The  stems  are  usually  hollow.  The  leaves  are  alternate, 
sometimes  opposite  at  the  base  of  the  stem,  and  as  a  rule 
pinnately  or  ternately  compound.  In  a  few  genera  (as 
Bupleurum,  Hydrocotyle  and  Oxypolis),  they  are  simple.  In 
Sanicula,  they  are  digitately  parted  or  lobed.  In  the  carrot, 
fennel,  and  others,  the  leaves  are  decompound.  The  petioles 
are  frequently  swollen  and  broadened  at  the  base  and  partly 
sheathe  the  stem.  There  are  no  stipules,  or,  if  present,  are 
very  small. 

Inflorescence  and  Flowers. — The  inflorescence  is  nearly 
always  an  umbel,  either  simple  or  compound,  but  occasionally 
a  head  (as  in  Eryngium).  The  umbel  is  so  characteristic 
of  this  group  of  plants  as  to  suggest  the  name  "  UmbeUif erae  " 
(literally  meaning  umbel-bearing).  In  a  compound  umbel, 
the  smaller  groups  of  flowers  are  designated  umbellets.  The 
umbel  as  a  whole  is  commonly  subtended  by  an  involucre, 
the  umbellets  by  an  involucel  (Httle  involucre) .  When  the 
inflorescence  has  an  involucre,  it  is  said  to  be  involucrate; 
when  it  has  involucels,  it  is  involucellate. 

The  flowers  (Fig.  218)  are  small,  mostly  regular,  perfect 
or  polygamous,  and  pentamerous.  In  some  instances,  the 
outer  flowers  of  the  umbel  are  irregular,  the  petals  pointing 
outward  being  somewhat  larger  than  those  pointing  inward. 
The  calyx,  when  present,  forms  a  tube  wholly  adnate  to  the 
S30 


UMBELLIFER^ 


531 


ovary;  the  limb  of  the  tube  is  absent,  or  divided  into  five 
inconspicuous  teeth.  The  corolla  consists  of  five  separate 
petals,  attached  to  the  base  of  the  calyx  tube;  the  tips  of  the 
petals  are  usually  turned  in,  and  emarginate  or  two-lobed. 
There  are  five  stamens,  curved  inward  in  the  young  flower, 
with  fihform  filaments  and  versatile  anthers.     The  single, 


^kamen 


Fig.  218. — Parsnip  (Pastinacasativa).  A,  median  lengthwise  section  of 
flower,  X  12;  B,  face  view  of  same,  X  12;  C,  dorsal  view  of  single  mericarp,  X 
2H;  D,  floral  diagram;  E,  schizocarp  with  mericarps  separating  at  maturity, 
X  2>^;  F,  cross-section  of  single  mericarp,    X  10.      {D  after  Strasburger.) 


inferior  ovary  consists  of  two  locules,  with  a  single  seed  in 
each,  and  of  two  distinct,  straight,  fiHform  styles  borne  on  a 
swollen  nectariferous  style  foot,  the  stylopodium  (Fig.  218). 
In  some  genera  (as  Apium,  celery),  the  stylopodium  is 
inconspicuous  or  wanting.  The  umbellifers  are  usually 
insect-pollinated.     Protandry  is  common. 


532  BOTANY  OF  CROP  PLANTS 

Fruit. — The  umbelliferous /m^'/  (Fig.  218)  is  very  charac- 
teristic. It  is  termed  a  schizocarp,  i.e.,  a  dry  fruit  of  two 
carpels,  these  separating  at  maturity  along  the  midline  or 
commissure  into  two  one-seeded  halves — the  mericarps. 
Each  individual  carpel  or  mericarp  is  indehiscent.  The  two 
mericarps  remain  attached  for  a  while  after  sphtting  by  a 
forked  stalk,  the  carpophore  (Fig.  218,  E).  At  the  summit  of 
the  fruit  is  a  swollen  nectary,  the  stylopodium,  giving  rise 
to  two  short,  persistent,  usually  outwardly  curved  styles. 
Each  mericarp  bears,  on  the  outside,  five  longitudinal  mem- 
branous or  corky,  ribs,  the  primary  ribs.  These  are  modifi- 
cations of  the  pericarp;  each  encloses  vascular  bundles.  In 
some  cases,  there  is  one  secondary  rib  in  each  of  the  four 
furrows  or  grooves  between  the  primary  ones,  thus  making  in 
many  instances  nine  ribs  (five  primary,  four  secondary)  to 
each  half  of  the  mature  fruit.  Within  the  grooves,  as  is 
best  seen  by  a  cross-section  of  a  mericarp  (Fig.  218,  F),  are  oil 
tubes  (vittae),  running  lengthwise  of  the  fruit.  These  tubes 
contain  secretions  of  balsams,  resins,  and  volatile  oils,  which 
impart  to  the  fruit  its  characteristic  odor  and  taste.  The 
fruit  may  be  bristly  (as  in  carrot)  or  smooth  (as  in  parsnip, 
and  many  others).  The  bristles  may  cover  the  fruit  (as  in 
Sanicula),  or  be  confined  to  the  ribs  (as  in  carrot).  Oil 
tubes  are  sometimes  obsolete  or  obscure  (.as  in  Conium, 
Hydrocoiyle,  Washingtonia).  If  distinct,  they  are  solitary 
(as  in  parsnip)  or  several  (as  in  Angelica,  Cymopterus). 
There  are  usually  two  or  more  oil  tubes  on  the  commissural 
side,  that  is,  on  the  side  that  is  contiguous  with  the  adjoining 
mericarp. 

The  fruit  is  either  flattened  laterally  (at  right  angles  to  the 
commissure),  or  flattened  dor  sally  (parallel  to  the  commis- 
sure), or  in  some  instances  not  flattened  at  all  (terete  or 
nearly  so).     The  one  seed  in  each  carpel  completely  fills  the 


UMBELLIFER^  533 

whole  cavity  and  is  usually  adnate  to  the  pericarp;  the  inner 
seed  faces  may  be  concave  or  flat.  There  is  considerable 
oily  endosperm  present  in  the  seed.  The  small  embryo  is 
imbedded  in  the  endosperm  near  the  hilum.  The  fruit  is  of 
greater  taxonomic  importance  than  any  other  portion  of  the 
plant.  Usually,  it  is  necessary  to  have  the  mature  fruit 
before  an  accurate  determination  can  be  made  of  a  species  in 
hand.  Keys  to  the  genera  and  species  are  largely  based  upon 
fruit  characters. 

Geographical. — The  carrot  family  is  one  of  north  temperate  regions,  not 
being  well  represented  in  the  tropics.  According  to  Britton  and  Brown,  there 
are  close  to  1,600  species  in  about  170  genera. 

Key  to  Genera  of  Economic  Importance 

Fruit  bristly,  Dauciis  (carrot). 
Fruit  not  bristly. 

Fruit  strongly  flattened  dorsally,  with  lateral  ribs  more  or  less  prominently 

winged  (Fig.  218,  F),  Pastinaca  (parsnip). 
Fruit  not  strongly  flattened  dorsally,  usually  more  or  less  laterally  flattened 
(Fig.  222,  B). 
Stylopodium  conical. 

Involucre  wanting;  leaves  pinnately  compound. 
Flowers  white.  Coriander  (coriander). 
Flowers  yellow,  Ftenictdum  (fennel). 
Involucre  present;  leaves  ternately  compound,  Canim  (caraway). 
Stylopodium  flat  or  wanting,  Apiiim  (celery  and  parsley). 

DAUCUS  CAROTA  (Carrot) 

Habit,  Root  and  Stems. — The  common  carrot  is  usually  a 
biennial,  sometimes,  however,  running  to  seed  the  first  year. 
During  the  first  season  of  growth,  there  is  a  storage  of  food  in 
the  enlarged  hypocotyl  and  prominent  tap  root,  both  of  which 
become  fleshy,  forming  the  so-called  "carrot."  Four  longi- 
tudinal rows  of  secondary  roots  are  given  off  from  the  tap 
root.  The  roots  are  much  thinner  and  woodier  in  the  wild 
form  of  the  carrot  than  in  cultivated  forms. 


534 


BOTANY   OF  CROP  PLANTS 


In  a  cross-section  the  of  "carrot"  the  following  tissues 
may  be  seen,  from  the  outside  to  inside:  (i)  periderm  (skin); 
(2)  cortex  and  phloem;  (3)  cambium;  (4)  central  region 
(wood  and  pith) .  A  good  carrot  is  one  with  a  proportion- 
ately large  cortex  and  phloem,  because  in  these  most  of  the 

sugar  is  stored.  During 
the  second  season  of 
growth,  a  rough,  hispid 
stem,  2  or  3  feet  high,  and 
with  spreading  branches 
is  sent  up  from  the 
"crown"  of  the  carrot. 

Leaves. — All  the  leaves 
are  decompound  (doubly 
compound).  The  lower 
ones  are  two-  to  three- 
pinnate,  the  segments 
linear  or  lanceolate,  den- 
tate, lobed  or  pinnatifid, 
the  upper  ones  smaller  and 
less  divided. 

Inflorescence  and 
Flowers.  —  The  inflores- 
cence is  a  compound 
umbel.  At  maturity,  the 
outermost  pedicels  bend 
inward,  the  whole  forming  a  structure  resembling  a  bird's  nest. 
The  involucral  bracts  are  long,  and  cleft  into  a  number  of 
narrow  lobes.  The  involucels,  at  the  bases  of  the  umbellets, 
are  made  up  of  entire  or  toothed  lobes.  The  flowers  are 
small  and  white,  the  central  one  of  each  umbel  often  purple, 
or  all  the  flowers  are  pinkish.  The  calyx  teeth  are  lacking. 
There  are  five  petals,  obovate,  and  with  the  tips  turned  in. 


Fig.  219. — Fruit  of  carrot  (Daucus 
carota).  A,  cross-section;  B,  external 
view.      {A,  after  Sargent).     B    X  lo. 


UMBELLIFER^ 


535 


In  the  outer  flowers,  the  petals  are  often  two-lobed.  The 
stylopodium  is  depressed  or  wanting,  and  has  two  curved 
stigmas. 

Fruit  and  Seed. — The  fruit  (Fig.  219)  is  oblong  and  dor- 
sally  flattened.  The  five  primary  ridges  of  each  carpel  bear 
long  hairs,  and  each  of  the  four  secondary  ridges  bears 
about  ten  long  spines,  at  the  ends  of  which  are  three  or  four 
hooked  hairs.  The  oil  tubes  (vittae)  are  soUtary  in  the  in- 
tervals, that  is,  under  the  secondary  ribs,  and  two  are  on  the 
commissural  side  of  each  mericarp.  The  seed  is  flattened 
dorsally,  and  the  face  plane  or  shghtly  curved. 

Geographical. — The  wild  form  of  Daucns  carota  is  a  native  of  Europe  and 
Asia.  It  has  become  common  throughout  North  America,  in  many  places 
proving  a  troublesome  weed.  All  the  cultivated  forms  of  carrot  are  con- 
sidered to  be  derived  from  this  one  wild  form. 


Fig.  220. — Types  of  carrots  (Daucus  carota).  A,  Garden  Ball;  B,  Early 
Scarlet;  C,  Oxheart;  D.  Chantenay;  E,  True  Danvers;  F,  Saint  Vallery;  G, 
Long  Orange. 


Varieties. — There  are  numerous  varieties  of  carrots  vary- 
ing as  to  size,  [shape,  color,  and  quahty.     As  to  shape  of 


536  BOTANY  OF  CROP  PLANTS 

the  vegetable,  varieties  may  be  divided  into  two  groups 
(Fig.  220). 

1.  Roots  distinctly  pointed,  tapering  (Long  Orange,  Saint 
Vallery). 

2.  Roots  blunt  at  the  tip,  not  pointed  (Early  Scarlet 
Horn,  Ox-heart,  Chantenay,  Stump-rooted  Half  Long  Red). 

The  roots  may  be  white  (Large  White,  White  Vosges, 
White  Belgian),  red  (Carentan),  orange  or  orange  red  (Early 
French  Forcing  Oxheart,  Long  Orange),  or  purple-violet 
(some  Egyptian  and  Spanish  varieties). 

Uses. — Medium-size  carrots,  particularly  those  with  yellow 
or  orange  flesh,  are  used  as  a  table  vegetable  and  for  the 
seasoning  of  soups  and  stews.  The  larger,  coarser  varieties, 
such  as  Large  White,  Large  Yellow  Belgian,  Danvers  and 
White  Vosges,  are  grown  for  feeding  stock  during  the  winter 
season.  The  yellow  coloring  matter,  carotin,  is  sometimes 
extracted  from  the  roots  and  used  for  coloring  butter. 

PASTINACA  SATIVA  (Parsnip) 

Habit,  Roots,  and  Stems. — The  parsnip  is  of  either 
annual  or  biennial  duration.  When  grown  from  seed,  a 
fleshy  hypocotyl  and  tap  root  are  first  formed;  these  consti- 
tute the  "parsnip"  vegetable.  In  the  wild  form,  the  root 
and  hypocotyl  are  thin,  tough,  and  woody.  During  the 
second  season,  a  branching  stem  is  sent  up  to  a  height  of  from 
2  to  3  feet.  The  tall,  erect  stems  are  grooved,  smooth  or 
somewhat  downy  pubescent,  and  become  hollow. 

Leaves. — The  lower  and  basal  leaves  are  petioled,  pinnately 
compound,  the  thin  segments  ovate  or  oval,  lobed,  incised 
or  dentate.  The  upper  leaves  are  sessile,  much  smaller  than 
the  lower,  and  not  so  deeply  lobed.  The  terminal  leaflet  of 
each  leaf  is  usually  three-lobed. 


UMBELLIFER/E  537 

Inflorescence  and  Flowers.-  The  tlowers  (l""ig.   221)  arc 
in  broad  compound  umbels  usually  with  7  to  15  main  "rays, 
each  terminated  by  a  small  umbellet.     There  are  no  involu- 
cres   and  involucels  in  the  [)arsnip,  thus  (lilU'rin.i^  markedly 


itiva). 


from  tin"  carrot.  The  llowers  are  >i'llo\v.  Tin-  calyx  teeth 
are  very  small  or  absent,  the  petals  incurved  and  small,  the 
stvloi)odium  depressed,  and  the  ovary  inferior. 

Fruit  and  Seed.-   The  fruit  (Fig.  218)  is  l)roadly  oval  and 
much   llattened  dorsally.     The  dorsal  and  two  intermediate 


538 


BOTANY    OF   CROP    PLANTS 


priniar}-  ril)sarL'  Ihrcad-likc,  while  the  lateral  ribs  are  expanded 
into  broad.  Hat  wings,  with  those  of  the  two  mcricarps  con- 
tiguous. 'I'he  oil  tubes  are  solitary  in  the  intervals;  there 
are  iour  on  the  dorsal  side  and  two  to  four  on  the  commissural 
side.  The  olive-green  seeds  are  llattened  dorsally.  The 
seeds  are  very  short-lived. 

Geographical. — The  wild  parsnip,  Paslinaca  saliva,  from  which  our  ciilti- 
valcd  variolics  arc  derived,  is  a  native  of  Europe.  This  wild  form  has  l)c- 
comc  naturalized  in  many  sections  of  Xortli  America,  occurring  as  a  weed 
along  roadsides  and  in  waste  places. 

Varieties.- — There  are  comparatively  few  parsnip  \arieties. 
rrobabl\'  the  most  popular  sorts  are  the  Guernsey  and  Hollow 
Crown.     Tn  both  of  these,  the  crown  is  concave. 


Fi.;. 


■Celery  (Apium  graveolens).     A,  schizocarp,  external,  X  15;  B. 
diagrammatic  cross-section  of  scliizocarp,    X  20. 


APIUM  (Celery  and  Parsley) 

Generic  Description.— Members  of  this  genus  are  annual 
or  perennial  herbs  with  pinnately  dixided  leaves.  The  white 
or  gveenish  flowers  are  in  compound  umbels.  The  involucre 
and  involucels  ma\'  be  present  or  wanting.     The  cal}x  teeth 


UMBELLIFER^  539 

are  absent.  As  in  many  umbellifers,  the  petals  are  turned 
in  at  the  tip.  The  fruit  (Fig.  222)  is  flattened  laterally, 
broader  than  long,  smooth  or  covered  with  protuberances. 
The  mericarps  have  pronounced  corky  ribs;  the  oil  tubes  are 
solitary  in  the  intervals,  with  two  on  the  commissural  side. 

Geographical. — There  are  about  i8  species  in  this  group,  distributed  chiefly 
in  the  Eastern  Hemisphere.  There  are  two  well-known  cultivated  species 
(parsley  and  celery)  both  of  which  are  natives  of  Europe,  and  an  indigenous 
species,  Apium  leplophyllimi.  These  three  species  are  distinguished  in  the 
following  key. 

Key  to  Principal  Spfxiks  of  Apium 

Flowers  greenish-yellow,  Apimn  petroselimim  (common  parsley). 
Flowers  white. 

Leaf  segments  broad,  Apium  graveolens  (celery  and  celeriac). 

Leaf  segments  narrow,  Apium  leptophyllum  (fine-leaved  marsh  parsley). 

APIUM  PETROSELINUM  (Parsley) 

Description. — Common  garden  parsley  is  a  biennial,  the 
first  season  throwing  out  a  dense  whorl  of  radical  leaves  that 
are  bipinnate,  triangular  in  outline,  and  with  the  segments 
ovate,  and  dentate  or  incised.  During  the  second  season, 
there  is  sent  up  an  erect,  highly  branched  stem,  i  to  3  feet 
high.  The  upper  leaves  are  also  bipinnate,  but  the  seg- 
ments are  linear-oblong  and  entire. 

The  inflorescence  is  a  compound  umbel  with  linear  involu- 
cral  bracts  and  awl-shaped  involucellate  bractlets.  The 
flowers  are  greenish-yellow.  The  fruit  is  ovate,  smooth,  and 
with  pronounced  ribs. 

When  large  parsley  seed  is  used  the  plants  from  them  have 
larger  and  earlier  foKage  and  are  more  capable  of  renewing  the 
tops  after  being  cut  back  than  plants  from  small  seed. 

Varieties. — As  to  leaf  characters,  there  are  two  types  of 
parsley : 


540  BOTANY  OF  CROP  PLANTS 

1.  Plain  Parsley. — ^Leaves  plain,  not  curled. 

2.  Double  Curled,  Dark  Moss-curled,  Fern-leaved  Parsley. — 
Leaves  curled. 

The  turnip-rooted  or  Hamburg  parsley  is  a  type  bearing 
a  small,  fleshy  root,  which  is  the  edible  part  of  the  plant. 

APIUM  GRAVEOLENS  (Celery  and  Celeriac) 

Description. — This  species  is  either  annual  or  biennial  in 
habit,  most  commonly  the  latter.  When  grown  from  seed, 
there  is  formed,  in  the  cultivated  sorts,  a  clump  of  leaves  with 
thick,  fleshy  leaf  stalks.  The  leaf  stalks  are  the  edible  por- 
tions of  common  celery.  If  the  plants  have  been  stunted 
or  set  back  in  their  development,  seed  stalks  may  be  sent 
up  the  first  season.  Of  course,  in  celery  growing,  the 
" seeders''  are  undesirable  and  every  effort  is  made  to  pre- 
vent their  appearance.  Normally,  however,  seed  stalks  are 
sent  up  from  the  short  rootstock  the  second  season.  This 
stem  is  erect,  glabrous,  and  i  to  3  feet  high.  The  leaves  are 
pinnately  compound  with  three  to  five  oval,  coarsely  toothed 
or  incised  leaf  segments.  The  small  white  flowers  are  in 
umbels.  Involucre  and  involucels  are  small  or  wanting. 
The  fruit  is  oval,  flattened  laterally,  and  has  corky  ribs. 
The  oil  tubes  are  sohtary  in  the  intervals  and  two  in  number 
on  the  commissural  side. 

Geographical. — Apium  graveolens,  the  wild  form  giving  rise  to  our  cultivated 
celery  and  celeriac,  is  a  native  of  Europe.  In  eastern  United  States,  it  has 
escaped  from  cultivation,  and  it  is  said  that  in  the  salt  marshes  of  California 
it  has  become  naturalized. 

Types  and  Varieties. — There  are  two  types  into  which  the 
cultivated  celery  has  been  modified  by  breeding  and  selec- 
tion: (i)  common  celery,  with  enlarged,  tender,  edible  leaf 
stalks,  and  (2)  celeriac,  "German  celery"  or  turnip-rooted 
celery  {A.  graveolens  var.  rapaceum),  with  a  fleshy,  turnip- 


UMBELLIFER.E  541 

like  rootstock,  2   to  4  inches  long.     These  rootstocks  con- 
stitute the  edible  portion  of  the  plant  (Fig.  223). 

There  are  two  general  types  of  the  common  celery:  (i) 
self-blanching  varieties — quick-growing,  very  tender,  easily- 
blanching  sorts,  especially  adapted  for  fall  and  early  winter 
use  (White  Plume,  Golden  Self-blanching).  Blanching  (see 
page  250)  is  secured  by  keeping  the  leaf  stalks  away  from  the 


Fig.   223. — Celeriac  (Apium  graveolens).     (After  Vilmorin.) 

Ught;  the  leaf  blades,  however,  are  permitted  to  grow  in  the 
light,  so  that  the  processes  of  food-making  proceed  in  a 
normal  manner,  and  the  stalk  is  not  stunted.  Chlorophyll 
is  formed  only  in  those  parts  of  the  plant  exposed  to  the 
light  directly.  Boards,  paper  or  earth  are  placed  about  the 
stalks  to  exclude  the  hght. 

(2)  Green   or   winter  varieties-r-not   as    quick-growing   or 
easily  blanched  as  those  of  the  preceding  type  and,  further- 


542  BOTANY  OF  CROP  PLANTS 

more,  with  better  keeping  qualities  when  stored  for  the  winter 
(Giant  Pascal,  Boston  Market,  Winter  Queen,  Giant  White 
Solid). 

All  cultivated  varieties  of  celery  require  cool  weather  and 
plenty  of  moisture  for  their  best  development;  they  are 
intolerant  of  excessive  heat.  Celery  culture  is  carried  on 
with  the  greatest  success  on  reclaimed  muck  soils  in  regions 
with  a  cool  climate. 

Uses. — Celery  is  grown  principally  for  the  thick,  fleshy 
leaf  stalks.  The  leaves  are  also  used  for  garnishing  and 
seasoning,  and  the.  seeds  are  used  for  flavoring  salads  and 
soups.  The  fleshy  root  of  celeriac  is  used  as  a  flavoring  or 
is  stewed  separately. 

References 

Coulter,  J.  M.,  and  Rose,  J.  N.:   Monograph  of  the  North  American  Um- 
belliferae.     Contr.  U.  S.  Nat.  Herb.,  7,  No.  i:  1-256,  1900. 


CHAPTER  XXXV 
VACCmiACEJE  (Huckleberry  Family) 

This  is  a  widely  distributed  family  occurring  in  tropical, 
temperate,  and  arctic  regions.  It  is  closely  related  to  the 
heath  family  {Ericacece)  which  possesses  such  well-known 
plants  as  kinnikinic  {Ardostaphylos  uva-ursi),  the  creeping 
wintergreen  {Gaultheria) ,  American  Laurel  (Kalmia),  Labra- 
dor tea  {Ledum),  Azalea,  Rhododendron,  and  trailing  arbutus 
{Epigaa  repens).  In  the  heath  family,  however,  the  ovary 
is  superior  instead  of  inferior  as  in  the  huckleberry  family. 
There  are  two  important  genera  from  an  agricultural  stand- 
point, Vaccinium  and  Gaylussacia.  The  former  genus 
includes  a  rather  large  number  of  species  grown  for  their 
fruit;  these  take  in  the  bilberry,  blueberry,  cranberry, 
huckleberry,  and  whortleberry.  Gaylussacia  spp.  are  known 
as  tangleberry,  blue  huckleberry,  and  dangleberry.  Gaylus- 
sacia may  be  distinguished  from  Vaccinium  by  its  ten-celled 
ovary,  with  one  ovule  in  each  cell.  In  Vaccinium  the  ovary 
is  four-  to  five-celled,  or  sometimes  eight-  to  ten-celled  by 
false  partitions. 

Habit. — The  plants  belonging  to  this  group  are  erect  or 
prostrate  shrubs  or,  in  a  few  instances  {e.g.,  Vaccinium 
arboreum,  the  farkleberry)  a  sinall  tree.  Some  South 
American  species  are  epiphytic. 

Leaves. — The  leaves  are  simple,  alternate,  often  thick 
and  leathery  and  sometimes  evergreen,  and  without  stipules. 

Inflorescence  and  Flowers.— The  flowers  are  solitary  in 
the  leaf  axils  (as  in  Chiogenes  hispidula,  the  creeping  snow- 
543 


544 


BOTANY  OF  CROP  PLANTS 


.^^ 


berry,   or    Vaccinium  membranaceum,   the   thin-leaved   bil- 
berry), or  in  racemes  (as  in  Vaccinium  virgatum,  southern 
,  black  huckleberry,  or  Vaccinium  oxycoccus, 

the  European  cranberry).  The  flower 
pedicels  are  usually  bracted.  The  small 
flowers  are  perfect,  sympetalous,  and  usu- 
ally actinomorphic  (Fig.  224).  The  calyx 
(Fig.  225)  forms  a  tube,  grown  fast  to  the 
ovary,  the  limb  (free  portion)  four-  to 
five-lobed  or  four-  to  five-cleft,  and  either 
persistent  or  deciduous.  The  sympetalous 
corolla  is  divided  into  four  or  five  lobes 
or  very  rarely  into  nearly  separate  petals,  as  in  the  cran- 
berries. The  corolla  may  be  either  globe-shaped,  bell- 
shaped,  urn-shaped,  or  tubular.     There  are  twice  as  many 


Fig.  224. — Floral 
diagram  of  Vaccin- 
ium. 


Fig.   225. — Flower  of  Vaccinium.     A,  median  lengthwise  section;  B,  external 
view. 


stamens  as  corolla  lobes,  and  they  are  usually  inserted  at 
the  base  of  the  corolla;  the  filaments  are  commonly  flattened, 
short,  and  either  free  or  united;  the  two-celled  anthers  are 


VACCINIACE^  545 

upwardly  prolonged  into  tubes,  and  open  by  a  terminal  pore 
(Fig.  225).  The  ovary  is  inferior,  four-  to  five-celled  or  eight- 
to  ten-celled  by  false  partitions,  and  has  a  filiform  style,  a 
small  stigma,  unmodified  at  the  tip,  four-  to  five-lobed  or 
four-  to  five-toothed,  and  one  to  several  ovules  in  each  locule. 
Fruit. — The  fruit  is  globular  and  either  a  many-seeded 
berry  (as  in  Vaccinium)  or  drupe-like  (as  in  Gaylussacia). 
The  seeds  are  small,  compressed,  and  have  a  bony  seed  coat, 
and  a  small  embryo  imbedded  in  a  fleshy  endosperm. 

VACcmroM 

The  representatives  are  shrubs  or  small  trees.  The  leaves 
are  lealhexy.  The  flowers  are  solitary  or  in  short  racemes. 
They  have  characters  as  described  above  under  the  family. 

Pollination. — Coville  describes  the  method  of  pollination 
in  a  blueberry.  It  is  quite  probable  that  this  will  hold  true 
for  most  Vaccinium  species.  The  bell-shaped  flower  is  in- 
verted, the  10  stamens  hang  downward  and  are  shorter  than 
the  style.  The  flat  filaments  form  a  close  circle  about 
the  style,  being  held  together  by  the  interlacing  mar- 
ginal hairs.  When  an  insect  visits  the  flower,  the  only  easy 
way  it  can  get  at  the  nectar,  which  is  situated  at  the  base  of 
the  stamens  on  their  inner  side,  next  to  the  style,  is  to  push 
its  proboscis  between  the  anther  tubes.  In  this  process,  the 
mature  pollen  grains  are  shaken  loose,  and  some  of  them  stick 
to  the  insect's  body,  to  be  carried  by  it  to  flowers  visited  sub- 
sequently. The  anther  pores  open  inward.  The  stigma  is 
top-shaped  and  the  very  apex  is  the  only  receptive  portion. 
Hence  the  rim  of  the  stigma  just  below  the  receptive  surface, 
prevents  the  falHng  pollen  from  reaching  this  surface.  In 
this  way  self-pollination  is  to  a  large  extent  prevented. 

If  pollen  from  the  same  plant  is  used  in  pollination,  the  fruit 
that  is  formed  remains  small  and  green,  and  later  drops  oiT, 

35 


546  BOTANY  OF  CROP  PLANTS 

This  fact  serves  to  emphasize  the  need,  in  the  propagation  of 
blueberries  by  cuttings,  of  making  the  plantation  from 
cuttings  of  a  number  of  different  bushes. 

Fruit. — The  fruit  is  a  many-seeded  berry.  It  matures 
about  two  months  after  flowering.  The  berries  are  most 
commonly  blue-black  in  color,  although  albino  forms  are 
known  to  occur.  The  calyx  is  permanently  attached  to  the 
fruit.  Berries  may  remain  on  the  bushes  a  month  or  more 
after  they  have  reached  maturity  without  losing  their  flavor 
or  firmness. 

Geographical. — The  genus  is  widely  distributed  in  the  northern  hemisphere, 
mostly  in  North  America  and  the  Himalayas.  It  includes  about  125  species, 
about  27  or  more  of  which  are  native  to  North  America. 


Key  to  Chief  Fruit-bearing  Species  of  Vaccinium 

Fruit  red  in  color. 
Stamens  included,  V.  vitis-idcea  (cowberry,  mountain  cranberry,  foxberry). 
Stamens  exserted. 
Leaves  ovate,  acute   at   the    apex;    stems   slender,    creeping;   berries 

globular,  V.  oxyccccus  (small  cranberry). 
Leaves   oval  or  oblong,  obtuse  or  retuse  at  the  apex;  stems  stout, 
creeping,  with^  ascending  branches;  berries  egg-shaped  or  oblong,  V 
macrocaipon  (American  cranberry). 
Fruit  blue  or  black  in  color. 
Plants  low,  seldom  over  2  feet  tall. 
Leaf  surfaces  free  of  hairs. 
Berries  blue. 
Leaves  shining  above,  F.  ccepitosum  (dwarf  bilberry). 
Leaves  not  shining  above,  V.  vacillans  (low  blueberry,  blue  huckle- 
berry). 
Berries  black. 
Flowers  solitary  in  leaf  axils,  V.  myrtillus  (whortleberry,  bilberry) . 
Flowers  in  groups  in  leaf  axils. 

Fruit  with  bloom,  V.  angusiifolium  (low  blueberry). 
Fruit  without  bloom,  V.  nigrum  (low  black  blueberry). 
Leaf  surfaces  hairy,  V.  canadense  (Canada  blueberry). 


VACCINIACE^  547 

Plants  tall,  3  to  12  feet,  and  spreading. 

Flowers  solitary  in  leal  axils,  I',  ovalifoliiim  (tall  or  oval-leaved  bilberry). 
Flowers  in  groups  in  leaf  axils. 

Fruit  blue,  V .  rorymbosum  (high  bush  IjJuebcrry,  swamp  huckleberry). 
l''ruit  black,   V.  alroco'ccum  (black  blueberry). 

GAYLUSSACIA  (Huckleberry,  Tangleberry,  Dangleberry) 

Description.-  ^Members  of  this  genus  are  shrubs  with  alter- 
nate and  entire  or  finely  toothed  leaves.  The  inflorescence  is 
a  raceme.  The  small  white  or  p'mk  flowers  are  on  two-brac- 
teolate  pedicels.  The  calyx  tube  is  short,  iive-lobcd  or 
live-toothed,  and  persistent.  The  stamens  are  10  in  number, 
and  their  anthers  open  by  terminal  pores.  The  fruit  is 
described  as  a  berry-like  drupe,  or  lo-celled  drupe  with  10 
seed-like  nutlets.  The  ''seeds"  are  each  covered  with 
endocarf). 

Geographical. — The  genus  is  distributed  throughout  North  and  South 
.'\merica.  It  possesses  about  40  species.  There  are  five  species  of  Gaylussacia 
growing  in  North  America. 

Kiev  ru  North  American  Species  of  Gaylussacia 

Leaves  evergreen,  tinely  toothed,  G.  bracltyceni  (box-huckleberry). 
Leaves  deciduous,  entire. 

Fruit  with  a  bloom,  G.  frondosa   (blue  huckleberry,  tangleberry,  dangle- 
berry). 
Fruit  without  a  bloom. 
Leaves  2  to  4  inches  long,  G.  ursiiut  (Carolina  JuickKberry). 
Leaves  i  to  2  inches  long. 

Bracts  small,  deciduous,  G.  rcsi)iosa  l^black  or  high-bush  huckleberry). 
Bracts  large,  persistent,  G.  dumosa  (dwarf  or  bush  huckleberry). 

Of  the  above  species,  G.  resinosa  is,  as  a  rule,  the  common 
black  huckleberry  on  the  market.  This  species  is  a  shrub,  i 
to  3  feet  high,  with  stilT  branches,  oval  or  oblong  leaves  that 
are  very  resinous  when  young,  a  few  pink  or  red  flowers  and 
sweet,  seedy,  black  fruit.  It  grows  in  sandy  soil  from  New- 
foundland to  Georgia,  westward  to  Kentuck}'  and  Manitoba. 


548 


BOTANY   OF  CROP  PLANTS 


CRANBERRIES 
Some  botanists  place  the  cranberries  in  the  genus  Oxycor- 
cus,  separate  from  the  blueberries,  huckleberries  and  bil- 
berries, which  are  included  in  the  genus  Vaccinium.  In 
Oxycoccus  the  corolla  is  deeply  four-cleft  or  four-divided, 
while  in  Vaccinium  it  is  bell-shaped  or  cylindric  and  divided 
only  at  the  very  apex.  We  have  placed  all  the  cranberries 
in  the  genus  Vaccinium.     There  are  two  principal  species  of 


y  (Vaccinivim  inacrocariH^n). 


cranberries  grown  in  America:  American  cranberry  (K(/f- 
cinium  macrocarpon)  and  the  small  cranberry  {Vaccinium 
oxycoccus).  These  are  distinguished  in  the  key  above.  It 
seems  that  the  appearance  of  the  flower  in  the  bud  has  prob- 
ably suggested  the  name  cranberry  or  ''craneberry."  Just 
before  the  flower  opens,  the  pedicel,  calyx  and  corolla  resem- 
ble the  neck,  head,  and  bill  of  a  crane. 

Vaccinium  macrocarpon  (Large  or  American  Cranberry) . — 
This  is  a  low,  slender,  creeping  plant  with  oblong  or  oval 


VACCINIACEiE  549 

leaves,  whitened  beneath,  and  with  rolled  margins.  The 
flowers  are  on  short  upright  one-year-old  shoots;  they 
occur  in  very  short  clusters;  the  corolla  is  hght  pink.  The 
berry  is  red,  ovoid,  oblong,  or  almost  globular.  At  the 
summit  of  the  fruit,  are  four  persistent,  short  calyx  lobes, 
bent  inward. 

This  species  is  found  wild  in  boggy  land  in  the  northern 
part  of  the  United  States,  adjacent  Canada,  south  along  the 
eastern  coast  to  Virginia  and  North  Carolina.  It  is  also 
found  in  South  America.  It  is  the  cranberry  that  is  culti- 
vated to  a  large  extent  in  the  cranberry  centers  in  this  coun- 
try— Cape  Cod,  New  Jersey,  Wisconsin,  Michigan  and  Min- 
nesota. The  cultivation  of  cranberries  in  the  United  States  is 
practically  confined  to  cool,  moist  boggy  regions.  Cran- 
berries are  grown  in  natural  or  artificial  bogs,  which  are  capa- 
ble of  being  drained  or  flooded  at  will. 

Types. — Corbett  divides  American  cranberries  into  four 
groups,  based  upon  fruit  shape. 

1.  Bell. — These  are  the  most  popular  and  include  such 
varieties  as  Early  Black  and  Centennial. 

2.  Bugle. — Mathews,  Howe,  Centerville,  Dennis. 

3.  Olive. — McFarlin's,  Howes,  Jumbo. 

4.  Cherry  or  Spherical  Cranberries. — Early  Red,  Arpin, 
Makepeace. 

Vaccinium  oxycoccus  (Small  Cranberry). — This  is  the 
cranberry  of  the  Old  World.  It  is  a  slender,  creeping  plant 
with  thin  stems,  4  inches  to  i  foot  long,  and  with  ovate,  acute 
or  acuminate  leaves,  dark  green  above,  whitish  beneath. 
The  flowers  are  very  similar  to  those  in  the  preceding  species. 
The  berry  is  red,  globular,  four-celled,  and  often  spotted  when 
young;  it  is  smaller  than  that  of  the  American  cranberry, 
although  considered  by  some  of  superior  quality. 

The  small  cranberry  is  a  native  of  alpine  and  subarctic 


55°  BOTANY  OF  CROP  PLANTS 

regions  of  Asia,  Europe,  and  America.  It  is  not  cultivated 
in  America  to  any  great  extent. 

Vaccinium  vitis-idaea  (Mountain  Cranberry,  Windberry, 
Wolberry,  Cowberry,  Foxberry).^This  is  a  low  evergreen 
shrub  with  creeping  stems  and  thick,  leathery  leaves.  The 
flowers  are  in  short,  terminal,  one-sided  clusters.  The 
berries  are  dark  red. 

This  plant  grows  wild  from  Massachusetts  to  Labrador, 
west  to  British  Columbia  and  Alaska.  Although  not  cul- 
tivated, the  natives,  particularly  of  Nova  Scotia,  gather 
large  quantities  of  this  wild  cranberry  and  ship  them  to 
eastern  markets. 

HUCKLEBERRIES  AND  BLUEBERRIES 

Both  of  the  above  names  are  applied  to  the  fruit  of  species 
of  Vaccinium  and  Gaylussacia.  However,  it  is  uncommon  to 
see  the  name  blueberry  given  to  the  fruit  of  Gaylussacia 
spp.  These  bear  lo  seeds  in  each  fruit,  and  although  not  as 
numerous  as  in  the  berry  of  Vaccinium,  are  more  trouble- 
some. There  are  two  general  types  of  blueberries:  high- 
bush  blueberries  (F.  corymbosum,  and  V.  atrococcum), 
and  low-bush  blueberries  {V.  canadense,  V.  angustifolium, 
V.  nigrum,  and  V.  vacillans). 

The  common  black  huckleberry  on  the  market  is  Gaylus- 
sacia resinosa. .  Vaccinium  angustifolium  is  a  rather  common 
low-bush  blueberry,  while  V.  corymbosum  is  the  species  most 
desirable  for  cultivation. 

References 

CoviLLE,  Frederick  V.:  Experiments  in  Blueberry  Culture.     U.  S.  Dept. 

Agr.  Bur.  Plant  Ind.  Bull.  193:  i-ioo,  1910. 
Davis,  W.T.:  High-bush  Blueberries.     Proc.  Staten  Island  Assn.  Arts  and 

Sci.,  2:  63-64,  1909. 


CHAriKR  WW  1 
OLEACEiE  (Olive  Family) 

Family  Description.— This  is  a  family  of  trees  t)r  shrubs. 
Tlic  h'dvcs  are  t)j)jK)site,  cxstipulate,  and  simple  or  pinnatcly 
comjiound.  'J'he  iiiJJorcscencc  is  a  panicle,  raceme.  CNine  or 
fascicle.  The  floivcrs  are  repjular,  and  polygamous  or 
dioecious;  the  small  calyx  is  four-lobed,  sometimes  entirely 
absent;  the  reguhir  corolla  is  four-parted,  or  of  four  distinct 
petals,  or  absent.  'J'herc  are  two  stamens,  attached  to  Ihe 
corolla  or  to  the  receptacle.  The  single  pislil  is  compound, 
with  a  two-celled  ovary,  in  each  of  which  there  are  a  few 
seeds,  a  short  style,  and  capitate  stigma;  sometimes  the 
style  is  absent.  The  fruil  is  cither  a  capsule,  samara,  berry, 
or  (]ru})e. 

Geographical,  and  Economic  Importance.-  'J^iere  are 
about  2  1  genera  and  500  species  distributed  widely  in  tem- 
perate and  tropical  regions.  The  most  im])ortant  repre- 
sentative is  the  olive  {Olca  curopa^a).  Other  well-known 
members  of  the  family  are  the  lilacs  {Syringa),  privet  (Ligus- 
Irum),  Jessamine  (Jasminnm)  and  ash  {Fraxinus). 

OLEA  EUROP(EA  (OUve) 
Description — 'J'he  common  olive  is  a  small  tree  20  to  25 
feet  higli.  All  fruit  is  borne  on  two-year-old  wood,  and  the 
same  wood  never  bears  twice.  The  lanceolate  leaves  are 
leathery,  evergreen,  entire,  smooth,  scaly,  and  arranged  op- 
j)osite]}'  on  the  stem.  The  floivcrs  occur  in  axilhiry  racemes  as 
a  rule,  although  terminal  inflorescences  are  more  or  less  fre- 
quent. The  flowers  are  usually  imperfect.  The  small  calyx 
is  four-toothed,  the  corolla  four-cleft,  white  or  whitish,  the 
stamens  two,  and  the  pistil  one.  'Yhc  fruit  is  a  pur[)lish  drupe. 
551 


552  BOTANY  OF  CROP  PLANTS 

'Jlu-  olive  is  probably  a  native  of  the  Mediterranean  re<,non. 
Its  cultivation  in  this  country  is  conhned  almost  entirely  to 


Fic.    227. — Olive    (Olca   eun.puja).      Branch    and    fruit.      (./•><;;«    ((////.    Agr. 
Exp.  Sl,t.) 

the  warm,  dry  portions  of  California.  'Yhc  olive  requires  a 
mean  annual  temperature  of  57°F.,  and  it  is  claimed  that  at 
no  time  should  the  temperature  go  below  t4°F. 


OLEACE^  553 

Seed  Germination. — If  olive  seeds  do  not  receive  some 
treatment  before  planting,  they  will  not  germinate  for  a 
year  or  more.  This  delay  in  germination  is  due  to  the  thick, 
stony  covering,  and  to  the  oil  present  which  inhibits  water 
penetration.  The  delay  in  germination  has  been  overcome, 
in  part,  by  various  means,  such  as  soaking  in  warm  water, 
soaking  in  alkaline  or  acid  solutions,  cracking  the  stones,  and 
clipping  the  apex  of  the  seed.  The  last  method  appears  to 
be  the  best. 

Propagation. — The  olive  is  very  easily  reproduced  vege- 
tatively;  in  fact,  cuttings  of  any  kind  will  grow.  For  propa- 
gative  purposes  use  may  be  made  of  green  cuttings  with  the 
leaves  on,  of  chips  from  old  trunks,  of  young  or  old  limbs, 
and  even  of  knaurs.  Knaurs  are  knots  or  excrescences  formed 
upon  the  trunks  of  old  trees.  When  limbs  2  or  3  inches  in 
diameter  are  used,  they  are  cut  into  lengths  of  i  or  2  feet, 
each  spHt  lengthwise,  and  planted  horizontally  with  the 
bark  up.  Sprouts  readily  arise  from  the  section  of  trunk, 
and  such  sprouts  may  be  allowed  to  continue  their  growth 
where  they  are,  or  be  made  into  green  cuttings. 

Uses. — Olives  are  eaten  either  in  the  green  or  ripe  state. 
They  are  usually  "pickled,"  and  left  whole,  or  "stuffed." 
Olive  oil  is  an  important  commercial  product.  The  best 
quaHty  of  olive  oil,  known  as  "Virgin  oil,"  is  made  from 
hand-picked  fruit.  The  fruit  is  crushed  so  as  not  to  break 
the  seed.  The  pulp  is  treated  with  water  and  again  pressed, 
yielding  a  product  which  is  employed  as  salad  oil.  The 
pressed  pulp  is  again  treated  with  hot  water,  and  subjected 
to  high  hydrauKc  pressure;  this  process  gives  an  oil  known 
as  "olive  oil  foots."  It  is  employed  in  the  manufacture 
of  soaps,  particularly  castile  soap,  and  as  a  lubricant.  An 
oil  is  also  extracted  from  the  seeds.  It  is  much  like  that 
from  the  pulp. 


CHAPTER  XXXVII 
CONVOLVULACE^  (Morning  Glory  FamUy) 


corolla 
tube 

-^'■slarmn 


The  representatives  of  this  family  are  found  chiefly  in  warm 
climates.  There  are  close  to  900  species  in  400  genera.  A 
number  are  of  economic  importance,  among  which  may  be 
mentioned  the  sweet  potato, 
man-of-the-earth  {Ipomcea  pan- 
durata),  used  as  food  by  the 
Indians,  moon-flower  {Ipomoda 
hona-nox) ,  morning  glory 
{Ipomcea  purpurea),  cypress  vine 
{Quamoclit  quamoclit)  and  the 
bindweeds  {Convolvulus  spp.). 

Habit. — Most  of  the  repre- 
sentatives of  this  family  are 
twining  or  trailing  herbs;  some 
tropical  species  are  shrubs  or 
trees,  often  with  a  milky  juice. 
Leaves. — The  leaves  are  alter- 
nate, exstipulate,  entire,  den- 
tate, lobed,  or  dissected. 
Inflorescence  and  Flowers. — The  flowers  are  in  an  axil- 
lary cyme,  or  sometimes  soHtary.  They  are  regular,  perfect 
and  sympetalous  (Fig.  228).  The  calyx  is  attached  below 
the  ovary,  five-parted  or  five-divided,  usually  persistent,  aiid 
imbricated  in  .the  bud.  The  corolla  is  plaited,  convolute,  or 
twisted  in  the  bud,  and  becomes  funnel-form,  salver-form, 
campanulate,  or  tubular,  with  a  five-angled,  or  five-lobed,  or 
entire  limb  (Fig.  228).  The  five  stamens  are  inserted  on  the 
554 


-ovari) 
cohx 


Fig.  228. — Flower  of  sweet 
potato  (Ipomoea  batatas),  length- 
wise section.     (After  Sargent-) 


CONVOLVULACE^  555 

tube  of  the  corolla  and  alternate  with  its  lobes;  all  are 
anther-bearing.  The  filaments  are  filiform,  or  dilated  at  the 
base,  and  equal  or  unequal.  The  anthers  are  two-celled,  and 
longitudinally  dehiscent.  The  ovary  is  superior  and  usually 
has  two  cells  (rarely  three  cells),  each  of  which  bears  two 
ovules.  In  some  instances,  the  ovary  is  falsely  divided  into 
four  to  six  cells,  each  with  a  single  ovule. 
Fruit.^ — The  fruit  is  a  capsule;  its  seeds  are  endospermous. 

Key  to  Important  Genera 

Stigmas  capitate  (knob-like). 

Stamens  and  style  exserted,  Quamoclit. 

Stamens  and  style  included,  Ipomosa. 
Stigmas  two,  filiform  or  oblong,  Convolvulus. 

IPOMCEA  BATATAS  (Sweet  Potato) 

Roots  and  Stems. — The  sweet  potato  is  a  sinistrorse-twin- 
ing,  trailing,  perennial  herb  with  very  much  thickened  roots. 
The  "sweet  potato"  itself  is  often  designated  as  a  "root 
tuber."  The  fleshy  roots  have  stored  within  them  large 
quantities  of  starch.  They  should  not  be  confused  with  the 
tubers  of  the  Irish  potato.  Sweet  potato  "tubers"  are  roots, 
while  Irish  potato  "tubers"  are  stems. 

Propagation. — In  the  propagation  of  sweet  potatoes,  these 
fleshy  roots  are  cut  lengthwise,  and  the  cut  surface  of  each 
piece  is  laid  against  moist  earth  until  it  produces  sprouts. 
Then  the  piece  is  further  cut  up  and  each  portion  replanted. 
It  is  necessary  to  leave  a  part  of  the  epidermis  in  order  that 
adventitious  buds  will  develop.  Sweet  potatoes  are  fre- 
quently propagated  by  vine  cuttings. 

Leaves.— These  are  alternate,  heart-shaped,  petiolate, 
dark  green,  and  glossy. 

Inflorescence  and  Flowers.— The  large,  purple,  con- 
spicuous   flowers    are    axillary,    solitary    or    cymose.     The 


5S6  BOTANY  OF  CROP  PLANTS 

sympetalous  corolla  is  i  to  2  inches  wide,  funnel-form,  and 
has  a  five-lobed  limb,  and  plaited  tube.  The  corolla  is  folded 
longitudinally  and  twisted  usually  to  the  right  in  the  bud. 
The  stamens  are  as  given  under  the  family  description.  The 
two-  to  four-celled  ovary  has  a  thread-like  style  which  bears 
one  or  two  stigmas.     The  fruit  is  a  capsule. 

In  northern  latitudes,  the  sweet  potato  rarely  blossoms, 
and  never  matures  seeds. 

Geographical,  and  Environmental  Relations. — The  original 
home  of  the  sweet  potato  is  the  West  Indies  and  Central 
America.  Since  the  sweet  potato  is  of  tropical  origin  it  is 
largely  grown  in  the  Southern  States,  the  five  leading  ones 
being  North  Carolina,  Georgia,  Alabama,  Louisiana  and 
Mississippi.  Ample  sunshine  and  high  temperatures  favor 
its  growth.  Although  a  heavy  rainfall  is  desirable  during  the 
first  part  of  the  growing  season,  the  maturing  of  the  roots 
proceeds  best  with  rather  dry  weather.  They  do  best  in 
well-drained,  Hght  soils. 

Closely  Related  Species. — The  southern,  juicy  varieties  of  sweet  potatoes 
are  called  "yams."  They  should  not  be  confused,  however,  with  the  true 
yams,  or  Chinese  potatoes  of  commerce,  which  belong  to  the  species  Dioscorea 
batatas,  in  a  family  (Dioscoreaceae),  closely  related  to  lilies.  This  is  a  tall 
climbing  plant  with  simple  cordate,  shining  leaves,  small,  white  flowers,  and 
large  tubers. 

Types  and  Varieties.— Sweet  potatoes  may  be  divided 
into  two  groups  upon  the  basis  of  the  amount  of  water  and 
sugar  present:  (i)  Dry  sweet  potatoes  are  ones  in  which  the 
flesh  is  dry,  mealy,  and  yellow;  they  are  the  sorts  most  de- 
sired in  the  Northern  States.  The  Jersey  type,  which  includes 
spindle-shaped  varieties,  is  probably  the  best  known.  (2) 
"  Yams"  are  sweet  potatoes  in  which  the  flesh  is  watery,  rich 
in  sugar,  soft  and  gelatinous  when  cooked.  They  are  the 
sorts  most  in  demand  in  the  South.     Common  southern 


CONVOLVULACEiE 


557 


sorts    ("yams")  are   Triumph,  Nancy  Hall,  Dooley  Yam, 
Vineless  Yam,  Sugar,  Southern  Queen,  Florida. 


Fig.  229. — Types  of  sweet  potatoes  (Ipomoea  batatas).  A,  Black  Spanish; 
B.  Shanghai;  C,  Big  Stem  Jersey;  D,  Red  Bermuda;  E,  Southern  Queen. 
{Modified  after  Corbelt.) 


Fig.  230. — Types  of  sweet  potatoes  based  upon  the  character  of  the  foliage. 
A,  entire  or  round;  B,  shouldered;  C,  deeply  cut  or  lobed.  {After  Price,  Texas 
Agr.  Exp.  Sta.) 


Leaf  Shape  as  Basis  of  Classification.— Price  has  classified  the  varieties  of 
sweet  potatoes  according  to  leaf  shape.     These  groups  are  as  follows: 

1.  Leaves  round  or  entire  (Fig  230,   A)    (Pumpkin,    Shanghai,  Southern 
Queen,  Big  Stem  Jersey). 

2.  Leaves  "shouldered,"  that  is  shallowly  and  broadly  notched  on  either 


SSS  BOTANY  OF  CROP  PLANTS 

side  near  the  apex  (Fig.  230,  B)  (Delaware,  Early  Golden,  Yellow  Jersey, 
Red  Bermuda). 

3.  Leaves  lobed  (Fig.  230,  C)  (Barbadoes,  Sugar,  Yellow  Yam,  Vineless 
Yam). 

Sweet  potato  varieties  may  have  skin  color  that  is  white,  straw,  red,  or 
purple. 

1.  Skin  white  (Vineless  Yam,  Early  Golden,  General  Grant). 

2.  Skin  straw  (Orange,  Delaware,  New  Jersey). 

3.  Skin  red  (Pumpkin,  Red  Bermuda). 

4.  Skin  purple  (Black  Spanish,  Brazilian). 

Uses.' — Sweet  potatoes  are  used  chiefly  as  a  human  food. 
Some  of  the  coarser  varieties  are  grown  for  hog  pasture.  The 
vines  have  some  value  as  a  stock  food.  Flour,  starch,  glu- 
cose, and  alcohol  are  minor  products  of  the  root.  Small- 
sized  sweet  potatoes,  known  as  "seconds,"  are  canned. 
Kiln-dried  sweet  potatoes  produce  a  product  very  similar  to 
corn  meal  in  its  chemical  composition. 

References 

Groth,  B.  H.  a.:  The  sweet  potato.     Contrib.  Bot.  Lab.  Univ.  of  Pa.,  4- 
1-104,  1911. 


CHAPTER  XXXVIII 
SOLANACE^  (Potato  Family) 

The  potato  family  is  a  large  one,  chiefly  tropical;  it  has 
about  1, 600  species  in  70  genera.  A  number  of  these  are 
important  medicinal  and  food  plants.  Here  are  included 
such  economic  forms  as  Red  or  Cayenne  pepper,  tobacco, 
common  Irish  potato,  eggplant,  tomatoes,  belladonna 
{Atropa  belladonna)  which  furnishes  the  atropin  of  commerce, 
thorn  apple  {Datura),  petunia,  etc. 

Habit  of  Plants. — Representatives  of  the  family  are  either 
herbs  (potato,  tobacco,  tomato),  shrubs  (Lycium  spp.),  vines 
(Solanum  dulcamara,  bittersweet),  or  trees  in  some  tropical 
species  of  Datura. 

Leaves — These  are  alternate,  rarely  opposite,  without 
stipules,  and  entire,  toothed,  lobed  or  dissected. 

Inflorescence  and  Flowers. — The  inflorescence  is  mostly 
cymose,  sometimes  imperfectly  racemose,  umbellate,  or 
paniculate.  The  flowers  (Fig.  232)  are  regular,  or  nearly  so, 
perfect,  and  vary  in  color.  The  calyx  is  inferior,  and  usually 
with  five  united  lobes.  The  corolla  is  sympetalous,  mostly 
fiveobed.  The  corolla  varies  considerably  in  shape:  rotate 
(tomato),  bell-shaped  {Phy sails),  funnel-form  {Lycium  vul- 
gare),  salver-form  or  tubular  (Petunia  spp.)  There  are  as 
many  stamens  as  corolla  lobes,  alternate  with  them,  and 
inserted  on  the  tube;  in  most  genera,  the  stamens  are  all 
equal  and  bear  perfect  anthers,  but  in  Petunia,  for  example, 
there  are  four  perfect  stamens,  the  fifth  being  very  much 
reduced  or  entirely  absent;  the  anthers  are  two-celled,  dehis- 
559 


560  BOTANY  OF  CROP  PLANTS 

cent  at  the  apex  or  along  the  sides.  The  single  ovary  is 
usually  two-celled  (rarely  three-  to  five-celled,  as  in  Ly- 
copersicon  spp.),  the  numerous  ovules  being  on  axile  pla- 
centas; the  style  is  slender,  simple,  and  the  stigma  terminal. 
Fruit. — The  fruit  is  either  a  berry  (potato,  tomato),  or  a 
capsule  (tobacco,  petunia).  In  both  cases,  it  bears  numer- 
ous seeds,  which  have  a  fleshy  endosperm. 

Key  to  Important  Genera 

Fruit  a  berry  (Fig,  233). 
Anthers  opening  by  a  terminal  pore  or  slit  (Fig.  232),  Solanum  (potato  and 

eggplant). 
Anthers  opening  longitudinally 
Flowers  white,  Capsicum  (pepper). 
Flowers  yellow,  Lycopersicon  (tomato). 
Fruit  a  capsule  (Fig.  244). 

Capsule  generally  prickly.  Datura  (thorn  apple,  Jimson-weed). 
Capsule  not  prickly. 

Flowers  paniculate  or  racemose;  stamens  nearly  uniform  in  length, 

Nicoliana  (tobacco). 
Flowers  solitary;  stamens  very  unequal,  Petunia  (petunia). 

SOLANUM 

Habit. — The  Solanums  are  either  erect  herbs  (as  S.  nigrum, 
the  black  nightshade,  and  the  common  potato,  etc.),  or 
climbing  herbs  (5.  dulcamara,  bittersweet).  In  most  species, 
the  stems  and  leaves  bear  a  stellate  (star-shaped)  pubescence. 

Leaves. — The  leaves  are  alternate,  exstipulate,  and  lobed 
orfpinnately  dissected. 

Inflorescence,  and  Flowers. — The  inflorescence  is  cymose 
(bittersweet),  umbellate  (black  nightshade),  racemose  {S. 
carolinense,  horse  nettle),  or  rarely  paniculate.  The  flowers 
(Fig.  232)  are  perfect  and  regular;  in  color,  they  are  white 
(5.  tuberosum  varieties  and  S.  nigrum),  blue  (S.  ceagni- 
folium,  silver-leaved  nightshade,  and  S.  tuberosum  varieties), 


SOLANACE^  561 

yellow  (S.  rostratum,  sand  bur),  or  purple  {S.  dulcamara). 
The  calyx  is  bell-shaped  or  rotate,  generally  five-parted  or 
five-cleft.  The  corolla  is  rotate  or  rarely  broadly  bell- 
shaped,  the  tube  very  short,  the  Hmb  plaited,  five-angled  or 
five-lobed.  There  are  five  stamens  inserted  on  the  throat  of 
the  corolla  (Fig.  232);  the  filaments  are  short,  the  anthers 
converge  around  the  style,  and  are  usually  dehiscent  by  a 
terminal  pore,  sometimes  by  a  short  introrse  terminal  sht, 
and  sometimes  longitudinally.  The  ovary  is  superior,  usu- 
ally two-celled;  its  style  is  slender  and  simple,  and  the 
stigma  terminal. 

Fruit. — The  fruit  is  a  many-seeded  berry;  the  calyx  is 
persistent  at  the  base,  and  in  some  species  {S.  rostratum) 
encloses  the  berry. 

Geographical. — There  are  about  900  species  of  Solatium,  widely  distributed, 
but  most  abundant  in  tropical  America. 

Key  to  Important  Species  of  Solanum 

Not  tuber-bearing. 

Plant  not  prickly  or  spiny. 
Erect  herbs  or  shrubs. 

Fruit  ovoid  or  egg-shaped,  yellow  with  purple  or  violet  streaks  or 
splashes,  often  4  to  6  inches  long,  S.  muricatum  (pepino,  melon 
pear).  "^ 

Fruit  a  small,  spherical  berry,  not  over  i  inch  in  diameter. 

Peduncles  ne-  to  three-flowered;  ripe  berries  green,  S.  Irijlorum 

(wild  tomato,  cut-leaved  nightshade). 
Peduncles  bearing  small  cymes,  three-  to  ten-flowered;  ripe  berries 
black,  S.  nigrum  (black  or  common  nightshade). 
Climbing  vines,  S.  dulcamara  (blue  bindweed,  bittersweet). 
Plant  prickly  or  spiny. 

Berry  not  enclosed  by  the  calyx. 
Flowers  light  blue  or  white;  fruit  a  small  spherical  berry,  S.  caroHnense 

(horse-nettle). 
Flowers  purplish}  fruit  large,  5.  melongena  (egg  plant). 
36 


5^2  BOTANY  OF  CROP  PLANTS 

Berry  enclosed  by  calyx,  S.  rostratum  (sand  bur,  buffalo  bur). 
Tuber-bearing.  * 

*NoTE. — Berthault  in  his  monograph  on  the  tuber-bearing  Solanums,  has  a 
key  to  37  species.     A  portion  of  this  key  is  here  included  (modified)  to  show 
the  relation  of  common  potato  to  some  wild  tuber-bearing  species. 
Corolla  rotate. 
Points  of  sepals  long  and  tapering. 
Leaves  oval,  S.  tuberostim  (common  potato). 
Leaves  elongated,  S.  immile. 
Points  of  sepals  long,  not  tapering  much;  leaves  oval,  5.  chiloense. 
Points  of  sepals  short. 

Anthers  straight,  smooth,  somewhat  elongated,  S.  utile. 
Anthers  swollen,  roughened,  5.  maglia. 
Corolla  star-shaped,  5.  janiesii,  S.  commersonii,  etc. 

SOLANUM  TUBEROSUM  (Potato) 

This  species  includes  all  the  varieties  that  are  of  value  for 
food.  They  are  usually  called  Irish  or  common  potato,  but 
also  white,  English,  and  round  potato.  • 

Habit. — The  potato  is  a  branched,  more  or  less  spreading 
herb,  growing  to  a  height  of  2  to  5  feet  or  more.  It  has 
annual  aerial  stems,  but  is  practically  perennial  by  means  of 
its  tubers  or  underground  stems. 

Roots. — Upon  the  whole,  the  development  of  the  root 
system  is  less  pronounced  than  in  most  other  crops.  The 
roots  are  fibrous  and  fine.  They  penetrate  the  soil  to  a 
depth  of  2  to  4  feet  and  frequently  extend  horizontally  2 
feet  or  more  from  the  plant. 

Stems. — Potato  stems  are  of  two  general  kinds  as  to 
medium  in  which  they  grow:  Underground  and  aerial.  The 
underground  stems  (Fig.  12)  are  slender  rhizomes,  or  are 
swollen  to  form  tubers  (''potatoes").  The  aerial  stems  are 
the  ordinary  foliage-bearing  stems.  The  discussion  of 
rhizomes  and  tubers  is  given  on  pages  29  and  31. 

Stem  (aerial)  .—The  aerial  or  foHage  stem  of  the  potato 
is  herbaceous  and  generally  erect  when  young,  but  usually 


SOLANACEyE 


563 


becomes  spreading  later.  "It  is  smooth  and  generally  solid. 
It  has  no  ribs  at  lust,  but  as  it  develops,  it  becomes  more  or 
less  quadrangular. 

Leaves. — Potato  leaves  are  compound  jiinnate,  with  more 


,U."Fl'>w 


luim  luhorosuni) 


or  less  petioled  leallets.  The  petiole  bears  a  number  of 
supplemenLar>-  leallets  which  vary  in  number  and  importance 
with  the  age  of  the  i)laiU.  'i'he  rachis  is  decurrent  (Fig.  12) 
on  the  stem.  The  leallets  are  oval,  acuminate,  and  the  base 
heart-shape  or  oblique  in  shape.  The  leaves  as  well  as  the 
stems  are  characterized  by  a  narcotic  smell.     At  the  begin- 


564 


BOTANY   OF  CROP   PLAXTS 


ning  of  their  development,  the  leaves  are  often  simple,  but 
they  increase  in  complexity  with  age.  The  single  terminal 
leaflet,  which  frequently  appears  alone,  is  soon  followed  b\- 
two  lateral  leaflets,  and  these  by  others,  so  that  the  leaf  soon 
becomes  distinctly  pinna titid. 

Considerable  diiTerences  have  been  found  to  exist  in  the 
appearance  of  the  leaves  of  the  ditTerent  agricultural  varieties. 

Flower  (Fig.  232). — The  corolla  is  tubular,  with  fixe  lobes. 


^-terminal  pore 
^anther    ' 


Fig.   232. — Potato  (Solanum  tuberosum).     .1. 
lengthwise  section;  C,  flora 


Ijcrry;   /> 
<li;i^;r;un. 


It  is  white,  yellow,  purple,  or  blue  in  color  and  i  to  i}  2  inches 
m  diameter.  There  is  a  single  whorl  of  five  stamens  which  al- 
ternate with  the  corolla  lobes,  and  are  attached  to  thi-  tube. 
The  stamens  are  straight,  and  bear  erect,  yellow  anthers  which 
are  longer  than  the  filaments  and  o[)en  onl}-  at  the  top. 

Two  kinds  of  pollen  grains  have  been  observed.  Those  of 
most  varieties  are  variable  in  size,  irregular  in  shape,  rough- 
ened, and  largely  impotent.  Those  of  the  other  type  are 
smooth,  spherical,  and  potent.  The  latter  kind  are  found 
only  on  varieties  which  bear  fruit.  .Some  varieties  produce 
both  kinds  of  pollen  grains,  but  such  [slants  do  not  always 


SOLANACE^  565 

produce  fertile  flowers.  Hence  while  the  presence  of  round 
pollen  grains  seems  to  be  necessary  to  the  production  of  fruit, 
their  presence  by  no  means  assures  that  the  ovary  will  be 
formed  or  fruit  produced.  The  ovary  consists  of  two  carpels 
with  numerous  ovules  in  each  locule. 

Opening  of  Flower  and  Pollination. — The  anthers  are 
mature  at  the  same  time  that  the  stigmas  are  receptive.  The 
flowers  have  been  found  to  open  between  5  and  6  o'clock 
a.m.  The  pollen  is  usually  shed  on  the  second  day  of  bloom- 
ing, and  at  this  time,  the  pistil  is  most  receptive.  The  an- 
thers open  at  the  top  by  a  pore  and,  in  some  cases,  spHt  for  a 
short  distance.  The  pollen  is  carried  by  the  wind.  The 
flowers  produce  no  nectar  and  are  not  visited  by  insects  to 
any  extent,  although  several  species  of  insects  have  been  re- 
ported as  visiting  the  flowers.  East  concludes  from  obser- 
vations of  his  own  (and  of  others)  that  self-fertilization  is 
natural  to  the  species.  The  flowers  wither  about  the  fourth 
day,  in  the  profuse-seeding  varieties. 

Some  writers  report  that  fragrance  is  correlated  with  pollen 
yield,  but  East  says  he  found  no  noticeable  fragrance  in 
American  varieties.  It  is  commonly  thought  that  potatoes 
do  not  fruit  as  freely  now  as  formerly,  due  to  the  fact  that 
large  production  of  tubers  has  caused  a  degeneracy  in  seeding 
power.  While  many  of  the  varieties  seldom  bloom,  and  more 
rarely  set  seed,  some  of  the  best  varieties  bloom  freely  and 
under  proper  conditions  set  seed.  Eraser  says,  as  a  result  of 
working  with  300  varieties,  many  of  which  were  grown  for 
several  years,  that  it  is  seldom  that  a  variety  will  not  bloom 
at  some  time  in  its  Ufe  and,  furthermore,  he  found  that  many 
of  the  heaviest  yielding  varieties  bloomed  as  freely  as  those 
of  less  value. 

In  many  varieties,  the  flowers  do  not  open.  In  the  Pearl 
variety,  Fitch  finds  that  tuber  productiveness  "is  universally 


566  BOTANY  OF  CROP  PLANTS 

proportionate  to  the  sexual  development  of  the  plant;  that 
the  most  degenerate  tuber  is  produced  on  the  plant  which 
carries  fully  developed  flowers  and  virile  pollen;  while  those 
plants  on  which  only  female  portions  of  the  flowers  appear  to 
be  fully  developed,  produce  tubers  intermediate  in  form  and 
yield,  and  that  the  best  tubers  and  the  largest  yield  are  pro- 
duced by  the  type  of  plant  whose  flower  buds  do  not  even 
swell."  Furthermore,  these  buds  do  not  show  any  other 
color  than  green  and  they  soon  wither  and  break  off. 

Fruit. — The  fruit  (Fig.  233)  is  a  globular  or  short  oval 
berry  with  two  locules  containing  numerous  seeds  attached 
to  the  thick  axil  placenta  and  embedded  in  a  green  acrid 
pulp.  The  fruit  is  called  by  various  names,  such  as  "potato 
ball,"  "potato  apple,"  or  "apple,"  but  is  commonly  referred 
to  as  the  "  seed  ball."  In  color  the  seed  balls  are  brown, 
purplish  green,  or  green  tinged  with  violet.  Single  fruits  may 
contain  from  a  few  to  as  high  as  200  or  300  seeds,  but  some- 
times no  seeds  are  produced.  Fitch  found  no  seeds  in  650 
seed  balls  of  Early  Rose.  One  seed  ball  from  a  Pearl  crossed 
with  a  Rual  contained  no  seed,  while  six  seed  balls  of  the 
reciprocal  cross  all  bore  abundant  seeds.  Removal  of  the 
early  tubers  induces  fruit-bearing,  while  removal  of  the 
flowers  is  said  to  encourage  tuber  development. 

Seed, — The  seeds  are  small,  kidney-shaped,  and  embedded 
in  the  green,  very  acrid  pulp  of  the  fruit. 

Germination  of  Seed. — Potatoes  are  seldom  propagated  by 
seed  except  for  the  production  of  new  varieties.  As  a  result, 
many  who  are  familiar  with  tuber  propagation  know  little  or 
nothing  about  seed  germination. 

Germination  of  seed  begins  in  about  five  to  seven  days  after 
planting,  being  complete  in  about  eleven  to  sixteen  days. 

Fig.  233. — Potato  seed  balls,  showing  a  cluster,  and  lateral,  sectional  and 
basal  views.     (After  Stuart,  U.  S.  Dept.  of  Agri.) 


S68 


BOTANY   OF   CROP   PLANTS 


ground  line 


The  primary  root  appears  first,  soon  becomes  curved,  and  is 
followed  by  the  axis  of  the  hypocotyl.  The  cotyledon  leaves 
are  smooth,  oval,  and  more  or  less  elongated,  while  the  first 
foliage  leaves  are  provided  with  unbranrhed  hairs. 

Development  of  the  Seed- 
ling.— -From    the   thirty-sev- 
enth to    the    fifty-sixth   day 
after     seeding,     the    stolons 
arise    (Fig.    234) ;     the     first 
pair   comes    from    the    axils 
of    the    cotyledon    leaves. 
These  slender  cylindrical 
stems     possess     small     rudi- 
mentary leaves.     They  trail 
along    on     the    ground    and 
finallx'     penetrate     the    soil. 
When    their   tips   strike   the 
ground,   they   begin  to  swell 
and  form  tubers.     Hence  the 
first    tubers    of     the     plant, 
grown    from     seed,    are    de- 
vel()[)e(l  at  the  tips  of  slender 
stolons  coming  from  the  axils 
of  the  cotyledon  leaxes.     Roots  soon  arise  from  the  stolons. 
Secondary  sLtjlons  appear  in  the  axilsof  the  first  foliage  leaves. 
Tubers  from  Seedlings. — Tubers  produced  on  seedlings 
are  usually  small  the  first  \ear.      However,   Fra/ier  rejjorts 
a  tuber  weighing  over   7   ounces   thai   was   formed  the  first 
year,  and  says  thai   the  Kurbank  [)olal()  was  full-sized  the 
first  year  from  seed.      U  is  rei)orted  from  Svalof  (Sweden) 
that  tubers  usually  attain  normal  size  and  type  after  about 
the  third  year  from  seed. 
Tuberization. — It  has  been  noted  prexiously  that  tubers, 


tuber 


Fig.  234. — Young  potato  plant  grown 
from  seed.      (After  Pcnival.) 


SOLANACE^  569 

developed  on  a  plant  grown  fron-i  seed,  come  at  the  tips  of 
stolons  arising  on  the  stem  above  ground.  However,  when 
the  tuber  as  a  cutting  is  used  in  propagation,  the  young 
tubers  form  at  the  ends  of  long,  thin  rhizomes  (underground 
stems)  which  arise  underneath  the  ground  from  the  main 
axis  or  stem  (Fig.  12).  The  length  of  the  stolon  seems  to 
be  constant  and  a  strong  variety  characteristic.  In  culti- 
vated varieties,  it  should  not  exceed  3  or  4  inches.  In  6'. 
commersonii,  it  is  reported  as  sometimes  reaching  a  length 
of  10  feet.  The  tubers  or  swollen  stems  bear  a  number  of 
buds,  and  these  buds  send  out  sprouts  when  the  tuber  is 
planted. 

As  a  rule,  the  tubers  are  formed  beneath  the  ground  as 
noted  above;  but  in  abnormal  cases,  or  when  disturbed  by 
diseases,  the  above-ground  stems  may  produce  tubers.  For 
example,  when  the  fungus,  Rhizoctonia,  which  shuts  off  the 
downward  movement  of  elaborated  foods  from  the  leaves  to 
the  underground  tuber-forming  stems,  is  active,  normal 
tuberization  under  ground  is  interfered  with  and  the  stems 
above  ground  will  have  a  tendency  to  swell  and  produce 
small  tubers.  This  phenomenon  is  often  indicative  of 
Rhizoctonia. 

Fungus  Theory  of  Tuberization. — In  general,  it  is  found 
that  darkness  and  low  temperature  favor  the  development 
of  potato  tubers.  Tuberization  is  also  facihtated  somewhat 
by  checking  the  growth  of  shoots  or  fruit. 

There  is  some  basis  for  the  theory  that  the  formation  of 
the  tubers  is  associated  with  the  presence  of  certain  fungi. 
It  is  certain  that  tuber  production  is  encouraged  in  certain 
orchids  when  the  stem  or  root  is  infected  with  the  proper 
fungus.  The  fungus  appears  to  check  the  growth  of  the 
terminal  bud  and  cause  the  development  of  hypertrophied 
cells. 


570  BOTANY  OF  CROP  PLANTS 

When  the  potato  was  first  introduced  in  France,  it  was 
found  that  when  tubers  were  planted  a  crop  was  produced, 
but  when  seed  was  sown  no  tubers  were  obtained.  From 
this  it  was  inferred  that  when  tubers  were  planted  they  in- 
fected the  new  ones,  while  the  seed,  free  of  fungi,  did  not 
furnish  a  supply  to  infect  the  stolons,  and  hence  tubers  could 
not  form.  However,  no  difficulty  is  now  experienced  in  se- 
curing tubers  from  seed  because  the  soil  has  become  inocu- 
lated with  the  proper  fungi.  If  this  theory  is  correct,  and 
there  seems  to  be  some  evidence  that  it  is,  the  potato  tuber 
is  in  reality  a  gall,  produced  by  a  foreign  organism. 

In  the  potato,  tuberization  has  been  induced  in  concen- 
trated solutions  of  sucrose  or  glycerin,  etc.,  independent  of 
fungi.  Similar  results  have  occurred  in  the  case  of  orchids, 
onions,  and  radishes.  From  this  it  seems  that  the  formatiou 
of  tubers  may  result  when  the  osmotic  pressure  in  the  cul- 
tural medium  is  high.  However,  this  alone  does  not  appear 
to  be  the  only  determiner,  since  different  results  follow  the 
use  of  glucose  and  glycerine  solutions  of  equal  pressure.  It 
certainly  seems  that  plenty  of  sugar  must  be  present  for 
starch  formation,  and  perhaps  also  for  tubers  to  form.  From 
this  fact,  that  a  more  concentrated  cell  sap  is  usually  present 
in  fungi  than  in  other  plants,  it  does  not  seem  unreasonable 
to  suppose  that  the  role  of  fungi  in  tuberization  consists  in 
raising  the  concentration  of  the  media  which  they  enter.  It 
has  actually  been  found  that  cultures  of  Fusarium  in  macer- 
ated potato  tuber  preparations  increase  the  concentration. 
In  this  connection,  it  is  suggested  that  low  temperatures  and 
dryness  of  soil  may  induce  tuberization  through  increasing 
the  concentration  of  cell  sap. 

History. — It  seems  ''that  the  potato  was  cultivated  and 
utiHzed  by  the  Chilean  and  Peruvian  people  before  the 
arrival  of  the  Spaniards.     In  1533,  Pizarro  found  the  Chileans 


SOLANACE.E 


;7i 


using  the  tubers  of  a  [)lant  as  their  i)riiui|)al  l"ot»«l.  There  is 
no  evidenee  that  he  or  his  party  inl  roihiecl  them  into 
Europe." 

Wild  plants  have  been  found  on  the  Peruvian  coast,  on 
the  mountains  of  Chile,  Central  America,  Mexico,  and 
southwestern    I'nited    Slates.     However,    without    a    di)ul)t 


Fig.   235. — The  wild  potato  of  southwest  United  States  (SuUinam  jamcsii). 
(After  Fitch.  Colo  Agr.  Exp.  Sta.) 


tliose  which  were  introduced  into  Kuroi)c  were  from  culti- 
vated plants  and  not  from  wild  tuberous  American  species. 
There  is  little  doubt  that  South  .\merica,  in  the  neighborhood 
of  (Juito,  is  the  place  from  wliich  the  potato  was  lirst  intro- 
duced into  S])ain  early  in  tlie  Si.xleenlh  cenlur_\-. 

\\\cv  a  careful  study  of  all  possible  axailablc  l_\  pes  and 
species  of  Sohmiim,  and  a  perusal  of  the  available  litrraturc 
and  records,  F.  Berthault  has  come  to  the  conclusion  that 
.V.  Iiihrrosiini  is  characterized  and  differentiated  from  all 
other  wild  tuberous  5(>/'//////».v  by  its  lloral  characters,  notablx' 
its  rotate  corolla,  and  its  cal>\  whith  is  always  mucronati' 
(sharp-pointed).     All  agricultural  \arieties  of  the  cultivated 


572 


BOTANY   OF   CROP   PLANTS 


plant  (potato)  have  been  found  to  correspond  to  these 
characters. 

Varieties. — There  are  at  the  present  time  over  500  named 
varieties  of  potatoes  in  the  United  States.  Many  of  these 
variety  names  are  found  to  belong  to  potatoes  which  are 
identical  in  all  respects.  Usually,  new  varieties  arc  the 
seedlings  of  established  varieties. 

The  latest  attempt  at  a  classilication  of  American  potatoes 
is  that  of  Stuart.     In  his  ''proposed  system  of  classilication" 


^^pendertr, 


Fig.    236. —  Diagrammatic  section  of  potato  tuber. 

he  gives  the  following  "groups":  Cobbler,  Triumph,  Early 
Michigan,  Rose,  Early  Ohio,  Hebron,  Burbank,  Green 
Mountain,  Rural,  Pearl,  and  Peachblow.  'J'uber,  sprout 
and  flower  characters  are  made  the  bases  of  distinction  of 
the  groui)s.  The  student  is  referred  to  Bull.  lyO,  U.  S. 
Dei^t.  Agr.  (Professional  Paper)  for  the  descriptions  of  these 
groups.  Fitch  has  also  proposed  a  classification  using  about 
the  same  characters. 
Tuber  Morphology. — The  [)()tato  tuber  is  made  up  of  a 


number  of  zones  or  la\ers  w 
follows  (Figs.  236  and  237): 

1.  Periderm  or  skin. 

2.  Corte.x. 

3.  Vascular  ring. 


lich  are  commonly  grou[)ed  as 


SOLANACE^ 


573 


4.  External  medulla. 

5.  Internal  medulla. 

According  to  Coudon  and  Boussard,  these  zones  (except- 
ing vascular  ring)  are  proportioned  (by  volume)  as  follows: 


Skin  (average  of  two  varieties) 

Cortex  (average  of  two  varieties) 

External  medulla  (average  of  five  varieties) . . . 
Internal  medulla  (average  of  five  varieties) .... 


Per  cent. 

8.79 
36.19 
34-I7- 
14-95 


-periderm 

oufer 
cortex 


inner 
~cortex 


Fig.  237. —  Microscopic  section  through  the  "skin"  and  portion  of  cortex  of 
potato  (Solanum  tuberosum). 

For  consideration  here,  these  zones  are  classified  as  fol- 
lows: 

1.  Periderm  or  skin. 

2.  Vascular  ring. 

3.  Parenchyma. 

(a)  Cortex. 

1.  External. 

2.  Internal. 

(b)  Medulla. 

1.  External. 

2.  Internal. 


574  BOTANY  OF  CROP  PLANTS 

Periderm  or  Skin.^ — The  stolon,  which  develops  into  the 
tuber,  possesses  the  true  stem  structure.  It  has  a  thin 
epidermis,  an  outer  parenchyma  tissue  or  cortex,  fibro- 
vascular  bundles,  and  an  internal  parenchyma  or  medulla. 
As  the  tuber  develops,  the  cortex  becomes  relatively  reduced, 
the  vascular  bundles  separate  and  the  medulla  becomes 
larger.  The  outer  layers  of  cells  of  the  cortex  also  undergo 
changes.  The  cells  of  these  layers  become  corky  and 
flattened,  and  so  arranged  that  the  vertical  walls  form 
straight  lines  and  do  not  overlap.  Their  walls  become 
suberized.  The  original  true  epidermis  gradually  dies  and 
disappears  entirely.  These  outer  corky  layers  of  cells 
constitute  the  periderm  or  skin  of  the  potato.  The  outer- 
most layers  of  periderm  spHt  off,  giving  some  varieties  a 
characteristic  rough  appearance.  The  cells  of  the  different 
layers  of  periderm  vary  in  size  and  shape  in  different  varieties. 
The  number  of  layers  is  usually  7  or  8,  but  it  varies  from  5 
to  as  many  as  13  and  even  17.  At  the  eyes,  the  periderm 
(skin)  becomes  thicker.   Lenticels  are  scattered  over  the  tuber. 

Some  claim  is  made  that  thick-skinned  varieties  are  of 
better  quality  than  thin-skinned  ones,  but  such  is  not  always 
the  case.  A  netted  or  rough  skin  develops  on  tubers  of  some 
varieties  as  they  mature  in  storage,  which  suggests,  that  a 
rough  or  netted  skin  in  these  cases  denotes  maturity.  Pos- 
sibly this  is  sometimes  the  source  of  the  common  idea  that  a 
rough-skinned  potato  is  of  superior  quality.  The  size  and 
type  of  netting  is  found  to  vary  with  the  variety  and  the  con- 
ditions under  which  grown.  Smoother  skins  are  usually 
found  on  potatoes  grown  on  sandy  soils  than  on  those  grown 
on  heavy  soils.  It  has  been  found  that  the  thicker  and 
rougher-skinned  varieties  stand  up  better  in  shipping,  and  are 
preferable  for  this  purpose  even  though  they  may  have  no 
greater  merit  in  other  ways. 


SOLAN  ACE^  575 

Vascular  Ring. — The  vascular  ring  consists  of  a  discon- 
tinuous circle  of  vascular  bundles:  It  is  located  between  the 
cortex  and  the  medulla.  At  the  eyes,  the  vascular  tissue  ap- 
proaches the  surface  of  the  tuber.  It  maintains,  however,  its 
proper  relationship  with  the  other  tissue,  i.e.,  between  cortex 
and  medulla.  The  cortical  layer  gradually  becomes  thinner 
as  the  vascular  bundles  approach  the  eyes.  The  vascular 
tissue  is  poor  in  starch.  The  vascular  ring  is  easily  recog- 
nized as  a  very  narrow  darkened  ring  near  the  edge  of  the 
exposed  surface  of  a  cut. 

Parenchyma. — Almost  the  entire  mass  of  tuber  tissue  in- 
side of  the  periderm  (skin),  except  the  vascular  tissue,  is 
parenchyma,  and  will  be  referred  to  as  such  in  this  discussion. 

The  parenchyma  is  divided  into  two  principal  parts:  the 
cortex,  and  the  medulla. 

Cortex.— The  cortical  layer  of  the  parenchyma  is  just 
within  the  periderm.  It  is  separated  from  the  medulla  by  the 
vascular  ring.  The  outer  cortex  is  made  up  of  smaller  cells 
than  the  inner  cortex.  The  cells  of  the  cortex  are  consider- 
ably smaller  than  those  of  the  medulla,  and  hence  the  density 
of  the  cortex  is  greater.  The  cortex  is  darker  in  color  than 
the  medulla,  which  is  probably  due  to  its  greater  density.  A 
thick  and  dense  cortex  indicates  a  potato  of  good  quality. 
A  thinner,  more  translucent  cortex  is  said  to  indicate  lower 
quahty.  The  periderm,  or  skin,  and  the  outer  layers  of  cor- 
tex are  removed  when  potatoes  are  peeled. 

Medulla. — The  medulla  consists  of  all  of  the  tuber  inside 
of  the  vascular  ring.  It  is  divided  into  two  parts,  the  exter- 
nal and  .the  internal  medulla.  When  a  thin  slice  of  potato  is 
held  up  to  the  light,  these  two  areas  are  easily  distinguished; 
the  external  medulla  appears  darker  and  denser;  the  lighter 
color  of  the  internal  medulla  is  due  to  its  greater  percentage  of 
water,  and  considerably  less  starch  and  other  solid  matter. 


576  BOTANY  OF  CROP  PLANTS 

The  internal  medulla  is  usually  more  or  less  star-shaped. 
Many  of  the  radiating  areas  of  internal  medulla  penetrate 
deeply  the  outer  medulla,  some  of  them  extending  to  the  eyes. 
In  some  tubers,  these  two  zones  are  more  or  less  intermixed, 
with  no  definite  zone  boundaries.  As  a  rule,  in  long  potatoes, 
the  central  area  is  very  much  elongated  and  with  lateral 
radiations,  while  in  many  round  potatoes  it  is  typically  star- 
shaped.  The  greater  the  size  of  the  internal  medulla  and  the 
more  its  ramifications  into  the  outer  area,  the  poorer  the 
quality  of  the  tuber,  since  it  means  a  larger  area  poor  in  starch 
and  hence  less  mealy  on  cooking. 

Shape.' — The  common  tuber  shapes  are  round,  oblong,  and 
elongated,  in  outline.  One  dominant  form  is  found  in  each 
variety  but  never  one  exclusive  form.  New  varieties  based 
on  tuber  form  are  produced  by  a  selection  of  tubers  and  are 
maintained  only  by  continued  selection. 

In  tuber  propagation,  there  appear  among  the  normal- 
shaped  tubers  a  number  of  aberrant  (diverging)  forms  which 
are  usually  in  the  minority. 

Color .^ — The  common  tuber  colors  are  yellow,  red,  violet  of 
different  shades,  and  variegated.  Bluish  forms  are  also 
known.  Color  variation  has  been  found  in  a  number  of 
cases.  In  propagation  by  cuttings,  yellow  and  streaked 
tubers  have  appeared  from  colored  ones  (red  and  violet). 
Yellow  tubers  have  given  red  and  violet  ones,  a  white  tuber 
has  given  two  red  and  two  white  tubers,  and  .one  with  a 
bluish  color  has  given  a  series  white  in  color.  The  Pearl 
with  a  brownish-white  or  a  well-russeted  skin  is  from  the 
Blue  Victor  which  has  a  purple  color  often  streaked  with 
white.  When  the  white  streaks  cover  an  eye,  the  tubers 
from  the  eye  usually  come  true  (white)  in  following  genera- 
tions. The  People's  variety,  also  from  the  Blue  Victor,  is  a 
deeper  brown  color  than  the  Pearl.     At  the  present  time, 


SOLANACE^  577 

white-fleshed  tubers  are  the  only  ones  accepted  in  American 
markets.  Yellow  flesh  is  correlated  with  a  strong  flavor  and 
a  poor  quality,  at  least  according  to  American  standards. 
A  number  of  yellow-fleshed  varieties  from  France  are  found 
to  be  gummy  and  hard  after  boiling.  They  are  considered 
by  the  French  to  be  of  prime  quality,  however.  In  this  coun- 
try, these  varieties  are  considered  of  good  quality  for  the 
making  of  salads  and  for  frying. 

Eyes  (Fig.  236). — The  buds  of  the  potato  tuber  usually 
occur  in  groups,  each  group  lying  in  a  more  or  less  depressed 
area.  Such  a  group  of  buds  is  called  the  "eye."  The 
depression  is  the  axil  of  a  scaly  leaf  which  was  in  evidence 
when  the  tuber  was  young,  but  later  disappears.  The  "eye 
brow"  ("eye  yoke")  is  the  line  above  the  depression — the 
line  which  separates  the  leaf  from  the  stem.  In  reality,  the 
eye  is  a  lateral  branch  with  undeveloped  internodes,  the 
whole  tuber  being  generally  a  much-branched  stem  and  not 
a  simple  shoot.  The  central  bud  in  the  "eye"  is  commonly 
the  largest  and  strongest. 

Fitch  has  noted  that  the  "eye-brow"  differs  noticeabl^r  in 
vigorous  and  in  degenerate  tubers.  In  the  latter,  ittis 
stronger  and  has  a  tendency  to  be  longer. 

Careful  study  shows  that  the  buds  or  "eyes"  are  arranged 
alternately  and  at  the  same  time  spirally  on  the  tuber.  Be- 
ginning at  one  end  of  a  tuber  and  proceeding  toward  the 
other  end,  at  the  same  time  turning  the  tuber,  usually  enables 
one  to  follow  clearly  the  spiral  arrangement. 

The  so-called  "seed  end,"  "rose"  end,  or  "crown"  of  the 
tuber  is  opposite  the  point  of  attachment  to  the  stem. 
The  "stem"  end  is  at  the  "base"  or  heel  of  the  tuber. 
The  eyes  are  more  numerous  and  more  vigorous  at  the 
seed  end.  Ordinarily,  the  terminal  bud  (at  the  "seed 
end")  is  the  strongest  and  under  proper  conditions  will  be 

37 


578  BOTANY  OF  CROP  PLANTS 

the  only  one  to  develop.  The  sprout  produced  by  the  ter- 
minal eye  is  spoken  of  as  the  "master  sprout."  The  eyes 
vary  in  different  varieties  from  very  deep  to  level  with  the 
surface;  the  latter  condition  results  in  smooth  potatoes. 
Deep  eyes  tend  to  hold  moisture;  as  a  result,  decay  is  invited 
and  hastened  when  the  potatoes  are  stored.  Smooth  varie- 
ties occasionally  give  rise  to  deep-eyed  tubers,  although,  as 
a  rule,  eye  depth  is  maintained  by  tuber  propagation.  It  is 
likely  that  the  deeper-eyed  plants  give  rise  also  to  smooth 
tubers  and  that  in  seed  propagation  the  same  results  follow 
as  in  the  case  of  form  and  color. 

The  number  of  eyes  varies  considerably  within  the  same 
variety;  in  one  case.  Rural  New  Yorker,  it  ranges  from  7  to 
28;  and  in  Early  Ohio,  from  7  to  22.  The  number  of  eyes 
affects  the  quaHty,  since  the  poorer  zone  of  the  potato  (in- 
ternal medulla)  extends  a  branch  to  each  eye,  thereby  in- 
creasing the  percentage  of  internal  medulla  at  the  expense 
of  the  two  outermost  valuable  layers. 

Germination  or  Sprouting  of  Tuber. — Potatoes  undergo 
some  changes  in  storage.  Not  only  do  they  lose  water  and 
decrease  in  weight  but  they  increase  in  sugar.  When  sprout- 
ing commences,  the  potato  becomes  sweeter,  due  to  the  con- 
version of  'starch  into  sugar  by  the  enzyme  diastase.  The 
most  vigorous  buds  are  the  terminal  ones.  The  tip  of  the 
main  sprout  grows  upward.  The  underground  stems  bear 
tubers  at  their  ends.  These  will  not  tuber  if  brought  to  the 
light  but  will  develop  into  ordinary  green-leafed  shoots. 

Physical  Composition  of  Potatoes. — In  all  varieties  the 
cells  of  the  cortex  are  much  smaller  than  those  of  the  medulla. 
In  general,  potato  varieties  are  characterized  by  their 
cellular  density  and  can  be  grouped  accordmgly.  The 
groups  are  not,  however,  clear-cut.  Cellular  density  is  an 
important  factor  to  consider  in  the  breeding  of  potatoes  for 


SOLANACE^ 


579 


table  use,  or  for  the  industries.  For  table  use,  only  those 
tubers  should  be  selected  which  have  small  cells  (high 
density),  and  for  starch  factories  only  those  with  large  cells 
(low  density).  Even  with  the  same  amount  of  starch  in  two 
varieties,  it  is  found  that  the  large-celled  one  is  the  more 
valuable  to  the  starch  industry,  due  to  the  fact  that  in  the 
small-celled  varieties  a  larger  number  of  the  cells  remain 
intact  and  do  not  give  up  their  starch  in  the  starch-removing 
process,  while  with  the  large-celled  varieties  fewer  starch 
cells  escape  being  broken  up.  In  France,  it  was  found  that 
rich,  compact  (heavy)  soils  produced  tubers  with  a  low 
cellular  density,  while  the  Hghter  soils  produced  tubers  with 
small  cells  and  high  density. 

Chemical  Composition  of  Potatoes. — A  number  of  analyses 
of  potatoes  have  been  made  in  this  country  and  in  Europe. 
Gilmore  gives  the  results  of  a  number  of  these  in  the  follow- 
ing  table: 


No.  of       No.  of 
analyses    varieties 


Quality 


Cornell 

Maine 

U.  S.  all  sources 

France: 

Condon  and  Boussard. 

Condon  and  Boussard. 

Coudon  and  Boussard. 

Coudon  and  Boussard. 


43 

i6 

136 


2. 170 
2.  200 

2.676 
2. 411 

2.36s 
2.090 


17-356 
18.037 
18.400 


Very  good. 
Very  good. 


.  798    Very  good. 
13.218    Good. 
14. 118  I  Passable. 
16.047    Poor. 


Water  and  nitrogen  increase  from  the  outer  to  the  inner 
zones,  while  the  starch  content  decreases. 

The  following  table  showing  composition  of  the  potato  is 
from  East: 


58o 


BOTANY  OF  CROP  PLANTS 


Variety 

Zone 

Dry 
matter, 
per  cent. 

Total   N. 
fresh  basis, 
per  cent. 

Total   N, 
dry  tjasis, 
per  cent. 

Rural 

Cortical 
Outer  Med. 
Inner  Med. 

Cortical 
Outer  Med. 
Inner  Med. 

20.95 
18.46 
14.04 

22  .  20 
19.41 
14.92 

0.46 
0.47 
0.45 

0.49 
0.52 

2  .20 

New  Yorker 

No.  2 

2.56 
3.23 

2.23 
2.63 
3-49 

Carman  No.  3  .  . .  . 

This  table  shows  that  the  dry  matter  decreases  from  the 
outside  to  the  inside  of  the  tuber.  The  nitrogen  content 
shows  an  increase,  on  dry  basis,  from  the  outside  to  the 
center,  although  on  a  fresh  basis  there  seems  to  be  no  regu- 
larity of  percentage,  probably  due  to  variability  in  water 
content.  The  inner  cells  of  the  cortex  contain  a  much  larger 
amount  of  starch  than  those  of  the  external  medulla,  which 
in  turn  contain  considerably  more  than  the  cells  of  the  inter- 
nal medulla.  The  outer  cells  of  the  cortex  which  are  removed 
with  the  skin  (in  peeling)  are  comparatively  low  in  starch. 

Starch  and  Sugar. — Potato  starch  grains  are  egg-shaped 
or  nearly  spherical  with  eccentric  markings,  and  with  the 
hilum  near  the  small  end.  Some  varieties  of  potatoes  are 
abundantly  suppKed  with  large  starch  grains  with  infre- 
quent small  ones,  while  in  other  varieties  the  reverse  is  the 
case.  No  correlation  has  been  found  between  the  size  of 
the  starch  grains  and  the  size  of  the  tuber  or  its  total  starch 
content.  In  general,  the  early  varieties  contain  large  starch 
grains  while  the  late  varieties  contain  a  larger  proportion  of 
small  grains.  Starch-grain  formation  is  very  slow.  At  first, 
many  small  grains  are  found,  most  of  which  later  increase  in 
size.  This  increase  in  size  begins  much  sooner  in  early 
varieties  than  in  late  varieties. 


SOLANACE^  581 

In  addition  to  starch,  potatoes  contain  noticeable  amounts 
of  sugar.  The  average  quantity  is  not  far  from  0.35  per 
cent.  This  sugar  is  lost  in  starch-making,  but  is  utilized 
in  the  manufacture  of  alcohol. 

"Mealiness." — In  estimating  cooking  quality  of  potatoes, 
meahness  is  the  most  important  consideration.  Mealiness 
depends  quite  largely  upon  the  amount  of  starch  in  the  cells. 
When  boiled  in  water,  the  starch  grains  expand  and  coalesce. 
If  there  is  sufficient  starch,  as  is  usually  the  case  in  the  cortex, 
this  expansion  ruptures  the  cell  walls,  freeing  their  contents 
and  producing  mealiness.  A  deficiency  of  starch,  as  is 
usually  the  case  in  the  cells  of  the  internal  medulla,  produces 
swelling  insufficient  to  rupture  the  cell  walls;  hence,  soggi- 
ness  results. 

As  has  been  shown,  the  different  zones  of  the  potato  vary 
considerably  in  starch  content,  the  cortex  being  highest, 
and  the  internal  medulla  lowest.  If  the  internal  medulla 
is  large  and  has  branches  extending  into  the  external  me- 
dulla, the  tuber  is  likely  to  be  hard  and  soggy  when  boiled, 
and  to  contain  zones  or  parts  which  will  not  mash  uniformly 
and  readily.  The  external  medulla  is  usually  well  stocked 
with  starch.  When  this  is  the  case,  and  when  the  starch  is 
distributed  uniformly,  leaving  no  ''water  areas,"  a  high 
degree  of  mealiness  can  be  expected  in  the  boiled  tubers,  a 
condition  necessary  for  high  table  quality  in  America. 

Quality  of  Potatoes. — The  standards  for  table  quality  in 
potatoes  vary  somewhat  in  different  countries.  The  more 
noticeable  differences  seem  to  be  between  France  and  the 
United  States.  East  notes  that  most  of  the  potatoes  which 
he  examined,  imported  from  France,  had  a  yellow  flesh,  a 
strong  flavor,  and  were  firm  and  soggy  after  boiling.  In 
France,  potatoes  are  commonly  cooked  by  frying  in  deep  fat. 
For  this  purpose,  a  potato  yellowish  in  color  which  holds  its 


582  BOTANY  OF  CROP  PLANTS 

form,  and  is,  as  a  result,  more  or  less  soggy  after  boiling,  is 
preferred.  These  characteristics  are  usually  found  in  po- 
tatoes which  are  low  in  starch  and  high  in  protein.  In  the 
United  States,  on  the  other  hand,  where  probably  nine-tenths 
of  the  potatoes  eaten  are  boiled,  a  white,  floury,  starchy  po- 
tato which  is  mealy  and  dry  when  cooked  is  demanded  for 
table  use.  In  Germany,  table  potato  standards  are  more  like 
those  in  the  United  States.  In  general,  it  is  considered  that 
for  table  use  in  thi§  country  potatoes  must  contain  about  17 
per  cent,  or  more  of  starch.  As  a  result  of  experimentation 
with  15  American  varieties,  East  says:  "It  is  quite  evident 
then  that  potatoes  having  as  far  as  possible  a  homogeneous 
flesh  and  containing  as  large  an  amount  as  possible  of  cor- 
tical and  outer  medullary  layers  in  proportion  to  inner  med- 
ullary layer,  should  be  of  the  finest  quahty." 

Degree  of  Maturity  and  Quality. — Analyses  in  the  United 
States  have  shown  that  the  "greater  part  of  the  total  nitro- 
gen is  developed  early  in  the  growth  of  the  tuber,  while  the 
starch  is  stored  up  later."  It  was  also  found  that  "  the  starch 
grains  of  immature  tubers  are  small  in  size  and  few  in 
number."     Tubers  increase  in  desirabiHty  with  maturity. 

Degeneracy  of  the  Potato. — The  "running  out"  of  potatoes 
is  a  common  observation.  New  varieties  are  put  on  the 
market,  are  very  productive  for  a  varying  number  of  years, 
then  they  usually  begin  to  "run  out"  or  degenerate. 

In  Colorado,  varieties  in  the  mountain  districts  do  not 
tend  to  run  out,  or  only  very  slowly,  the  tendency  apparently 
being  easily  overcome  by  seed  selection,  while  in  the  Greeley 
district,  on  the  plains,  at  an  altitude  of  4,600  feet,  the  sexual 
tendencies  and  consequent  degeneracy  seem  to  overcome 
other  influences,  such  as  selection.  At  Svalof  (Sweden)  the 
opinion  is  held  that  in  a  variety  of  potatoes  "there  is  no 
period  of  old  age."     On  the  other  hand,  degeneracy  is  be- 


SOLANACE^  583 

lieved  to  be  the  result  of  "factors  which  hinder  the  normal 
development  of  the  plants  and  tubers  or  invite  disease." 
Stewart  recently  describes  forms  of  degeneration  known 
as  leaf-roll,  curly-dwarf,  mosaic  and  spindUng-sprout.  He 
found  that  the  progeny  of  plants  with  normal  foliage  and 
high  yield  may  very  suddenly  degenerate  into  dwarfish  plants 
affected  with  the  above-mentioned  diseases.  The  leaf-roll, 
curly-dwarf  and  mosaic  troubles  are  passed  from  generation  to 
generation  by  means  of  the  tubers.  The  nature  of  spindling- 
sprout  is  not  this  well  known.  The  observations  are 
significant  in  that  they  show  that  seed  selection  may  not 
always  insure  against  "running  out."  It  is  claimed  by  the 
Svalof  investigators  that  more  vigorous  seed  tubers  are  pro- 
duced in  cool,  moist  conditions  than  in  hot,  dry  regions.  This 
view  is  also  held  by  Fitch  who  worked  in  Colorado.  The 
cause  of  this  increased  vigor  is  another  question.  It  may  be 
due  to  a  well-developed  vascular  system  in  the  tuber  or  an 
abundance  of  diastase  at  the  sprouting  season.  Investi- 
gators express  the  view  that  "where  suitable  sorts  are  used, 
and  where  suitable  tubers  of  these  sorts  are  utiHzed  for  seed- 
ing purposes  each  year,  the'  standard  of  a  variety  may  be 
maintained  indefinitely  under  all  favorable  conditions  of  soil 
and  climate."  Hence Jt  seems  that  the  inherent  tendency 
to  degenerate  is  perhaps  no  stronger  in  potatoes  than  in  other 
crops,  but  that  they*are  more  widely  and  strongly  influenced 
by  environmental  conditions  than  are  most  crops.  It  is  re- 
ported that  at  Svalof  the  variety  Dala,  introduced  about  150 
years  ago  in  the  province  of  Delarne,4s[^still  one  of  the  best 
sorts  grown  there. 

Environmental  Relations.— The  potato  is  a  native  of  the 
high,  cool  regions  of  Mexico  and  South  America.  In  the 
United  States  it  thrives  best  in  a  cool,  moist  climate  as  is 
evidenced  by  the  fact  that  the  five  leading  potato  States 


584  BOTANY  OF  CROP  PLANTS 

touch  the  Canadian  border.  It  is  well  adapted  to  elevation 
up  to  8,000  feet  in  the  Central  Rocky  Mountains.  Smith  has 
shown  that  the  potato  makes  its  best  development  in  those 
sections  of  the  country  where  the  mean  annual  temperature 
is  between  40°  and  So°F.,  and  where  the  mean  for  July  is  not 
over  7o°F. 

The  plant  is  grown  on  both  heavy  and  light  soils,  but  the 
latter  are  preferred;  upon  these,  the  plant  is  less  subject  to 


Fig.   238. — Percentage  of  the  world's  supply  of   potatoes  produced  in  the 
different  countries  in  19 14. 

disease,  the  tubers  are  of  better  quality  and  smoother,  and 
come  to  maturity  more  quickly. 

Uses  of  Potatoes. — Potatoes  are  put  to  the  four  following 
chief  uses:  (i)  human  food;  (2)  commercial  starch;  (3)  stock 
food;  and  (4)  alcohol.  Potatoes  rank  second  to  the  cereals  in 
importance  as  a  food  of  northern  peoples.  They  are  fed  to 
all  classes  of  stock,  especially  hogs.  In  the  dried  state,  they 
have  been  fed,  in  Germany,  to  cattle  and  horses  with  good 
results. 

Potato  Starch.— The  potatoes  are  first  soaked  for  several 
hours  in  water,  then  washed,  and  finally  reduced  to  a  pulp 


SOLANACE^  585 

by  rasping  machines.  The  pulp  is  passed  through  sieves, 
which  separate  the  fiber  from  the  hquor  containing  starch. 
The  hquor  is  allowed  to  stand,  and  during  this  time  white 
starch  settles  in  layers  at  the  bottom  of  the  receptacle.  The 
starch  is  drawn  off,  purified  by  allowing  it  to  run  over  tables, 
similar  to  those  used  in  the  purification  of  corn  starch  (page 
184),  and  finally  dried.  "Culls"  are  profitably  employed  in 
starch  manufacture. 

Alcohol. — In  Germany,  the  potato  is  used  extensively  for 
alcohol  manufacture.  In  this  country,  it  is  too  expensive 
for  this  purpose.  The  process  of  converting  the  starch  to 
alcohol  is  very  similar  to  that  used  in  the  manufacture  of 
alcohol  from  corn  starch. 

Production  of  Potatoes.' — The  world's  output  of  potatoes 
in  1912  was  5,872,953,000  bushels.  Of  this  amount,  Ger- 
many produced  1,844,863,000  bushels,  or  about  31  per  cent, 
of  the  total.  Russia  proper  ranked  second  with  a  production 
of  925,775,000  bushels.  France  third  with  552,074,000 
bushels,  and  the  United  States  fourth  with  420,647,000 
bushels.  The  five  leading  potato  States  in  1915  were  Minne- 
sota, Wisconsin,  New  York,  Maine  and  Michigan. 

SOLANUM  MELONGENA  (Eggplant,  Guinea  Squash) 

Description. — This  species  is  an  annual,  erect,  branching 
herb,  finally  becoming  subwoody,  2  to  3  feet  tall,  woolly  or 
scurfy,  and  spiny.  The  leaves  (Fig.  239)  are  large,  6  to  9 
inches  long,  sinuately  lobed,  ovate  or  ovate-oblong,  thick, 
becoming  almost  smooth  above  but  remaining  densely  hairy 
beneath.  The  flowers  are  solitary  or  in  small  clusters  in  the 
axils  of  branches;  the  calyx  is  woolly  or  spiny,  the  corolla 
purphsh  and  pubescent  (Fig.  239).  Parthenocarpy  has  been 
observed  in  this  species.     Artificial  pollination  is  practiced 


586  BOTANY  OF  CROP  PLANTS 

to  insure  fruit  production.  The  fruit  is  a  berry,  3  to  6  inches 
in  diameter,  smooth,  and  varying  in  color  (Fig.  239).  Egg- 
plant is  a  native  of  India.  All  cultivated  varieties  require 
high  temperatures.  They  are  usually  transplanted.  They 
are'used  exclusively  as  a  table  vegetable. 


Fig.  239. — Egg  plant  (Solanum  melongena).     A,  mature  fruit;  B,  leaves;  C, 
single  flower. 

Types  and  Varieties.— Bailey  has  divided  the  eggplants 
into  three  varieties,  as  follows : 

I.  S.  melongena  var.  esculentum  (Common  Eggplant). — 
The  plants  are  tall  and  stout,  the  leaves  large  and  thick,  and 
the  fruit  large  and  usually  spherical  or  oblong.  There  are 
forms  in  this  group  with  purple  fruit  (Black  Pekin,  New  York 


SOLANACE^  587 

Improved,  Giant  Round  Purple)  and  others  with  white  or 
striped  fruit  (White  Chinese,  Long  White,  White  Egg). 

2.  5.  melongena  var.  serpentinum  (Snake  Eggplant). — The 
plants  are  medium  to  tall,  the  leaves  large,  and  the  fruit  long 
and  slender. 

3.  S.  melongena  var.  depressum  (Dwarf  Purple  Eggplant). — 
The  plants  are  small,  weak,  and  spreading,  the  leaves  small, 
the  flowers  small,  and  the  fruit  small  to  medium,  pear- 
shaped,  and  purple  (Early  Dwarf  Purple). 

LYCOPERSICUM  (Tomato) 

Habit  of  Growth,  and  Stems. — The  tomatoes  are  annual 
or  short-lived  perennial,  coarse,  branching  or  feebly  cHmbing 
herbs,  that  vary  in  size  and  form  with  the  species,  climate, 
and  methods  of  culture.  The  upright  growing  tomatoes 
{L.  esculentum  var.  validum),  have  a  low,  stiff,  and  erect 
growth  form.  L.  esculentum  var.  grandifolium  is  a  tall  sort 
with  a  few  large,  entire  leaflets.  In  the  currant  tomato  {L. 
pimpinellifolium),  and  cherry  tomato  (L.  cerasiforme) ,  the 
branches  are  usually  weak  and  even  trailing  in  habit.  The 
pear  tomato  {L.  pyriforme)  has  an  erect  and  strong  habit  of 
growth. 

Roots. — The  root  system  of  tomatoes  is  fibrous  and  not 
extensive.  It  does  not  penetrate  far  into  the  soil  and  is 
usually  short-lived. 

In  the  transplanting  of  tomatoes  from  the  seed  bed  to  the 
garden,  it  is  the  practice  to  allow  the  seedlings  to  wilt  before 
they  are  reset.  Under  these  conditions  the  fine,  tender 
rootlets,  and  root  hairs  are  largely  destroyed,  but  the  plant 
promptly  throws  out  a  vigorous  cluster  of  new  ones.  In 
fact,  the  new  set  of  roots  possesses  greater  vigor  than  those 
on  a  seedling  that  has  not  been  allowed  to  wilt;  in  the  latter 
case  the  roots  are  not  injured  beyond  recovery,  and  it  ap- 


588  BOTANY  OF  CROP  PLANTS 

pears  that  their  recovery  prevents  the  prompt  development 
of  new  ones. 

Leaves. — The  leaves  are  usually  alternate,  always  com- 
pound, odd-pinnate,  and  petioled.  In  all  tomatoes  except 
L.  esculentum  var.  grandifolium  and  possibly  L.  pimpinelli- 
folium,  the  leaflet  margin  is  toothed  or  lobed. 

Inflorescence  and  Flowers. — The  flowers  are  commonly 
in  raceme-like  cymes,  or  in  racemes  (as  in  currant  tomato). 
However,  even  in  the  currant  tomato  the  racemes  are  often 
branched  at  the  tip.  The  flowers  are  perfect,  regular,  and 
pendant.  The  calyx  is  five-  to  six-parted;  the  segments  are 
Hnear  or  lanceolate,  persistent,  and  increase  in  size  with  the 
development  of  the  fruit.  The  corolla  is  rotate  or  wheel- 
shaped,  cleft  into  usually  five,  sometimes  more,  lobes;  the 
tube  of  the  corolla  is  short.  There  are  five  stamens  (some- 
times more)  attached  to  the  corolla  tube;  the  filaments  are 
very  short,  and  the  anthers  open  by  a  longitudinal  sHt  on 
the  inner  side;  they  are  elongated,  connate  or  connivent. 
There  is  one  pistil  bearing  a  single  style  and  an  ovary,  which 
is  usually  two-celled  (more  than  two-celled  in  cultivated 
tomatoes)  and  has  a  central,  fleshy  placenta. 

Pollination,  Fertilization,  and  Development  of  the  Fruit.— 
In  the  maturing  of  the  flower,  the  style  elongates  and  pushes 
the  receptive  stigma  through  the  tube  formed  by  the  anthers. 
In  some  instances,  this  elongation  occurs  prior  to  the  dehisc- 
ing of  the  anthers,  hence  eliminating  the  possibiHty  of  self- 
pollination.  Sometimes  the  anthers  shed  pollen  at  the  time 
the  stigma  is  pushed  upward,  and  in  the  growth  of  the  stigma 
it  rubs  against  the  dehiscing  surface  of  the  anthers.  Stigmas 
remain  receptive  for  several  days.  However,  it  is  known 
that  greenhouse  tomatoes  do  not  set  fruit  well  unless  arti- 
ficially pollinated,  as  is  commonly  done  by  jarring  the  plants 
at  the  time  of  anther  dehiscence.  Natural  cross-poUination 
seldom  occurs. 


SOLANACE/E  5^9 

Extensive  experiments  made  by  Fletcher  and  Gregg  with 
f^reenhoiise  or  forced  tomatoes  showed  that  self-fertiUzed 
blossoms  set  fruit  as  well  as  cross-fertilized  ones.  Further- 
more, there  was  practically  no  difference  in  the  appearance 
or  weight  of  the  fruit,  and  no  difference  in  the  number  of  cells. 

Parthenocarpy.— This  phenomenon  is  not  at  all  uncommon 
in  tomatoes.  By  this  is  meant  the  ripening  of  the  fruit 
without  the  fertilization  of  the  ovules.  Such  fruits,  of 
course,  possess  no  gcrminative  seeds. 

Abnormal  Tomatoes. — Munson  has  found,  in  crossing 
tomatoes,  that  the  amount  of  pollen  placed  on  the  stigmas 
affects  the  size  of  the  fruit.  Two  stigmas  in  the  same  flower 
chister  were  given  different  amounts  of  pollen:  one  abun- 
dant i)olIen,  the  other  lo  to  20  grains.  With  plenty  of 
pollen,  normal  fruit  resulted,  while  with  scanty  pollen,  small 
and  fleformed  fruit  resulted.  In  the  first  case,  there  was 
abundant  seed,  while  in  the  latter,  only  a  few  seeds.  One- 
sided tomatoes  result  when  pollen  falls  upon  one  side  of  the 
stigma  only.  It  is  undoubtedly  commonly  true  that  small 
and  irregular  tomatoes  are  caused  by  an  insufficient  sui)ply 
of  pt)llen. 

The  Mature  Fruit— The  fruit  is  a  true  berry  (Fig.  240). 
The  wild  form  of  our  common  garden  tomato  US',  csniloiluni) 
has  a  two-celled  fruit  with  a  rather  (lr\-  placenta.  'i"he  cells 
are  delinite  in  both  number  and  shape.  C'ultixaled  tornis 
of  the  common  garden  tomato  have  a  number  ol  cells  in  the 
fruit;  thev  are  indehnite  in  both  nuinl)er  and  shape,  and  the 
placenta  is  exceedingly  lleshy.  The  fewest  celled  fruits  are 
eonsi.lered  nean-st  the  original  tyi)e.  The  pear  and  cherry 
tomatoes  l)oth  have  two-celled  fruit,  'i'he  calyx  is  persist- 
ent, adhering  to  the  base  of  the  fruit.  The  fruit  \aries  in 
shape,  color,  and  smoothness  of  surface.  The  seeds  are 
numerous  and  small. 


59° 


BOTANY  OF   CROP  PLANTS 


Geographical. — All  the  species  in  this  genus  are  natives  of  South  America. 
iJunal,  in  DeCandoUe's  Prodromus,  gives  lo  species  of  Lycopersicnm;  this 
number  is  reduced,  however,  by  some  writers.  Tomatoes  are  warm  season 
"vegetables"  that  require  transplanting  in  central  and  northern  latitudes. 

Important  Species  and  Varieties, — There  is  a  difference  of 
opinion  whether  to  consider  certain  forms  of  tomatoes 
species  or  only  varieties.     For  example,  Bailey  recognized 


but  two  cultivated  species  of  Lycopersicnm:  L.  esculenluni, 
the  common  tomato,  and  L.  pimpincllijolinin,  the  currant 
tomato.  L.  esculenlum  is,  according  to  Bailey,  dixided  itUo 
the  following  varieties: 

1.  L.  esculenlum  var.  vulgare,  garden  tomato. 

2.  L.  esculenlum  var.  cenisiforme,  cherr}-  tonuito. 

3.  L.  esculenlum  var.  l)yriformc,  pear  or  plum   tomato. 

4.  L.  esculenluni  var.  validum,  upright  tomato. 

5.  L.  esculenluni  var.  grand  if olium,  large  leaf  tomato. 

L.  pimlyincllifoliuni  is  not  subdi\idcd.     On  the  other  hand, 
'I'rai}'    regards   as   distinct   species:  L.   pimpinellijolium,   L. 


SOLAN ACE^  591 

cerasiforme,  L.  pyriforme,  and  L.  esculentum,  including  under 
the  last  the  varieties  vulgare,  validum,  and  grandifolium. 

The  above  types  of  tomatoes  may  be  artificially  distin- 
guished by  the  following  key;  in  all  instances  cultivated  forms 
are  understood. 

Key  to  Types  of  Cultivated  Tomatoes 

Fruit  in  long  racemes  or  branched  clusters;  berries  red,  currant-like,  Currant, 

German,  raisin  or  grape  tomato. 
Fruit  in  short  racemes  or  branched  clusters. 

Plants  low,  stiff,  and  erect,  having  much  the  appearance  of  a  potato  plant; 

leaves  small,  curled,  Upright  tomato. 
Plants  taller,  the  branches  weaker  and  more  spreading. 

Leaves  very  large,  about  two  pairs  of  almost  entire-margined  leaflets, 

Large-leaf  tomato. 
Leaves  of  medium  size,  numerous  pairs  of  leaflets  the  margins  of  which 
are  toothed  or  lobed. 
Fruit  pear-shaped,  Pear  tomato. 
Fruit  globular  or  angular,  not  pear-shaped. 

Fruit  globular,  smooth,  red  or  yellow,  from  H  to  ^i  inch  in  diameter, 

two-celled,  Cherry  tomato. 
Fruit  varying  somewhat  in  shape,  surface,  and  color,  larger  than 
preceding,  many-celled.  Common  garden  tomato. 

The  common  tomato  (var.  vulgare)  has  undergone  consid- 
erable modification  as  the  result  of  cultivation.  As  compared 
with  the  small  two-celled  fruit,  with  thin  walls  and  a  dry 
placenta,  and  in  some  instances  with  distinct  grooves  on  the 
surface,  the  cultivated  forms  are  larger,  many-celled,  the 
walls  and  placenta  are  thick  and  fleshy,  and  the  fruit  surface 
smooth.  There  are  three  general  groups  of  the  common 
tomato:  fruit  angular,  fruit  apple-shaped,  and  fruit  oblong. 

The  cherry  tomato  (var.  cerasiforme)  has  small  globular, 
red  or  yellow  two-loculed  fruit.  The  pear  tomato  (var. 
pyriforme)  has  small  red  or  yellow,  two-loculed  pear-shaped 
fruit.  The  upright  tomato  (var.  validum)  looks  much  like 
the  potato  plant  in  its  growth  habit.     The  large-leaf  tomato 


592  BOTANY  OF  CROP  PLANTS 

(var.  grandifolium) ,  of  which  the  Mikado  may  be  taken  as  a 
type,  is  distinguished  from  the  other  varieties  by  its  large 
leaves  with  only  a  few  (normally  two)  pairs  of  leaflets. 

Closely  Related  Forms. — The  husk  tomato  {Phymlis  pubescens)  and  the 
strawberry  tomato  {Physalis  pubescens  and  P.  alkekengi)  are  distinguished 
from  Lycopersicum  spp.  in  that  the  calyx  becomes  enlarged,  inflated,  and  en- 
tirely covers  the  srtiall  berry.  The  fruit  is  esteemed  by  some  for  preserving, 
or  making  pies,  or  for  eating  raw. 

The  tree  tomato  {Cyphomandra  betacea),  a  tropical  plant,  has  a  fruit  similar 
in  taste,  at  least,  to  that  of  the  common  tomato.  This  plant  also  belongs  to 
the  SolanaCeae,  but  may  be  distinguished  from  Lycopersicum  by  its  woody 
habit  of  growth. 

History. — The  tomato  is  still  fomid  in  the  wild  state  in 
South  America.  The  Spanish  explorers  carried  the  fruit  to 
southern  Europe  where  it  was  used  as  a  food  long  before  it  was 
eaten  by  the  people  of  northern  Europe.  It  was  early  known 
in  England  and  America  as  the  ''Love  Apple."  A  prejudice 
against  the  tomato  existed  for  a  long  time,  no  doubt  due  to 
its  alliance  with  the  nightshades.  Now,  however,  it  is 
a  favored  article  of  diet,  and  from  500,000  to  600,000  acres 
are  devoted  to  its  growth  annually  in  the  United  States  and 
there  are  as  many  as  175  different  varieties  offered  by  seeds- 
men. 

Uses. — Tomatoes  are  commonly  used,  fresh  or  canned,  as 
a  table  vegetable.  Large  quantities  are  made  into  catsup. 
Such  varieties  as  Red  Plum,  Yellow  Plum,  Red  Pear-shaped, 
Red  Cherry,  and  Burbank's  Preserving  are  used  quite  ex- 
tensively for  pickling. 

CAPSICUM  ANNUUM  (Peppers) 

Description. — This  species  is  either  an  annual  or  biennial 
herb,  2  to  5  feet  tall,  and  sometimes  partly  woody  at  the  base. 
In  temperate-  regions,  the  plant  is  cultivated  as  an  annual, 
while  in  warmer  climates  it  is  often  biennial.     The  leaves  are 


SOLANACEJE 


593 


ovate  and  entire.  The  flowers  (Fig.  241)  are  solitary,  or 
in  twos  or  threes.  The  ri7/v:v  is  five-lobecl,  truncate,  obcon- 
ical,  cup-shaped  or  funnel- 
form.  The  corolla  is  white, 
rotate,  usually  ilve-lobed, 
with  the  lobes  valvate. 
There  arc  five  sUimcns,  some- 
times si.\  or  seven,  attached 
near  the  base  of  the  corolla; 
the  bluish  anthers  dehisce 
longitudinally.  The  ovary  is 
usually  two-celled,  rarely 
three-celled,  and  bears  a 
thread-like  style,  and  numer- 
ous ovules.  The  fruit  (Fig. 
242)  is  a  berry,  red  or  green 

in  color,  and   short  cylindrical  or  globular  in  shajK'. 
are  main'  seeds  in  each  fruit. 


longitudinal 
section  of  pepper  flower  (Capsicum 
annuum).      X  2. 


There 


I'l  lengthwise  sections  of  the  fruit  of  pepper  (Capsicum 
annuum;. 


3^5 


594 


BOTANY   OF   CROP    PLANTS 


Geographical. — This  species  has  never  been  found  wild.     But  it  is  quite  well 
established  tiiat  the  entire  genus  Capsinim  had  its  origin  in  tropical  America. 


Fig.  243. — Fruits  of  peppers  (Capsicum  annuum).  A,  Oxheart  (C. 
annuum  cerasiforme) ;  B,  Cherry  (C.  annuum  ccrasifera) ;  C,  Celestial  (C.  an- 
nuum abbreviatum);  D,  Chilli  (C.  annuum  acuminatum);  E,  Long  Cayenne 
(C.  annuum  acuminatum);  F,  Long  Yellow  (C.  annuum  longum);  C,  tabasca 
(C.  annuum  conoides);  //.  Sweet  Spanish  (C.  annuum  grossum) ;  /.Ruby 
King  (C.  annuum  grossum);  /.  Bell  (C.  annuum  grossum);  K,  Squash  (C. 
annuum  grossum).      {Afler  Irish.) 


Tlie  temperature  requirements  of  peppers  arc  similar  to  those  of  eggfiiants 
and   tomatoes.      Their  season  of  growth   is  so  hmg  tliat   they  .irr  unalile   to 


SOLAN ACE^  595 

produce  a  full  crop  before  frost,  except  in  the  Southern  States,  unless  started 
under  glass. 

Other  Species. — The  only  other  species  of  Capsicum  of  any  importance  is 
C.  frutescens.  This  is  a  shrubby  perennial  6  to  lo  feet  high.  Its  fruit  does 
not  ripen  well  in  northern  latitudes.  The  fruit  is  red,  small,  and  is  often 
called  "bird  pepper." 

Types. — Irish,  in  his  excellent  monograph  of  the  genus 
Capsicum,  places  the  numerous  commercial  varieties  into 
seven  tj'pes  or  botanical  varieties  (Fig.  243).  The  following 
key  to  these  .types  is  taken  (verbatim)  from  this  work. 

Key  to  Botanical  Varieties  of  Capsicum  Annuum 

Fruit  oblong-linear. 

Calyx  usually  embracing  base  of  fruit. 

Fruit  usually  less  than  i}i  inches  long;  peduncles  about  as  long  or  longer, 
C.   annuum   conoides    (Coral    Gem,  Tabasco,   Cayenne,  Orange-red 
Cluster). 
Fruit  usually  more  than  i}-i  inches  long;  peduncles  shorter. 
Leaves  and  fruit  fascicled;  fruit  erect,  C.  annuum  fasciculahim  (Red 

Cluster,  Yellow  Cluster). 
Leaves  and  fruit  not  fascicled,  C.  annuum  acuminatum  (Chilli,  Long 
Cayenne,  Nepal  Chili). 
Calyx  not  usually  embracing  base  of  fruit,  except  in  the  Ivory  Tusk  variety, 
C.  annuum  longum  (Black  Nubian,  Long  Red,  County  Fair,  Cardinal, 
Long  Yellow,  Ivory  Tusk). 
Fruit  oblate  or  oblong,  truncated,  deeply  lobed,  furrowed  and  wrinkled;  flesh 
mild,  K  2  to  ^i  inch  thick,  C.  annuum  grossum  (Monstrous,  Sweet  Spanish, 
Bell,   Sweet  Mountain,  Golden  Dawn,  Ruby  King,   Brazilian  Upright, 
Golden  Upright,  Squash). 
Fruit  subcorneal,  ovate  or  elliptical,  slightly  longer  than  broad,  %  to  2  inches 
long;  caly^  not  embracing  base,  C.  annuum  abbreviatum  (Celestial,  Etna, 
Kaleidoscope,  Red  Wrinkled,  Princess  of  Wales). 
Fruit  generally  smooth,  oval,  spherical,  cherry  or  heart-shaped,  %  to  i)^ 
'     inches  in   diameter;  calyx  seated   on   the   base,  C.  annuum   cerasiforme 
(Little  Gem,  Cherry,  Oxheart). 

Composition. — All  varieties  of  pepper  are  more  or  less 
pungent.  The  principle  which  imparts  the  pungent  taste  is 
a  crystalline  nitrogenous  compound  called  capsaicin.  In  the 
smaller   peppers    (Coral    Gem,    Tabasco,    Chilli,    Cayenne 


596  BOTANY  OP  CROP  PLANTS 

Cherry)  the  pungency  is  in  the  pericarp  as  well  as  in  the  pla- 
centa and  seed.  In  larger  varieties  (Squash,  Bell,  Sweet 
Mountain),  the  pungent  taste  is  located  for  the  most  part 
about  the  seeds,  while  the  fleshy  pericarp  is  "mild." 

Uses. — Medicinally,  the  red  pepper  is  used  in  a  great 
variety  of  ways.  Probably  its  most  important  use  is  as  a 
condiment,  Cayenne  Pepper  being  the  common  form.  This 
is  made  by  grinding  up  the  entire  fruit  to  a  fine  powder. 
Pepper  sauce  is  the  unground  fruit  preserved,  in  brine  or 
strong  vinegar.  Tabasca  Pepper  and  Tabasca  Catsup  are 
examples  of  this.  Chilli  con  carne  is  a  mixture  of  small, 
finely  ground  peppers  and  meat.  Peppers  are  commonly 
used  in  tamalas,  also  in  pickles  and  salads,  while  bell-shaped 
and  squash  varieties  are  used  as  mangoes.  Some  varieties, 
such  as  Little  Gem  and  Prince  of  Wales,  are  grown  for  orna- 
mental purposes. 

NICOTIANA  (Tobacco) 

Habit. — Most  representatives  of  this  genus  are  tall,  stout 
herbs.  Several  (as  N.  glauca  and  N.  tomentosa)  grow  to  a 
height  of  10  feet  or  more.  S.  wigandioides  is  half-shrubby. 
They  are  annual  or  perennial  in  habit,  and  for  the  most  part 
sticky-pubescent;  they  have  a  strong  odor,  and  narcotic, 
poisonous  properties. 

Leaves.' — The  leaves  are  simple,  alternate,  mostly  large, 
entire  or  wavy  along  the  margin,  petioled  (in  N.  glauca),  or 
sessile  and  decurrent. 

Inflorescence  and  Flowers. — The  inflorescence  is  a  terminal 
raceme  or  panicle.  The  flowers  are  large  and  vary  in  color: 
white,  yellowish,  yellowish-white,  greenish,  purphsh,  or  rose. 
The  calyx  is  synsepalous,  five-cleft,  and  usually  persists  in 
the  fruit.  The  corolla  is  salverform  or  funnelform,  five- 
lobed,  and  the  tube  is  longer  than  the  limb.     There  are  five 


SOLAN  ACE.E  597 

stamens  attached  to  the  corolla  tube;  the  filaments  are  slen- 
der, and  the  anthers  split  lengthwise.  The  two-celled  ovary 
bears  a  single,  slender  style,  and  a  capitate  stigma. 

Fruit. — The  fruit  is  a  two-celled  capsule  bearing  numerous 
very  small  seeds;  it  spHts  into  two  or  four  valves  at  maturity. 

Geographical  Distribution  and  Economic  Importance. — 
The  genus  includes  about  50  species,  mostly  of  the  American 
tropics.  A  number  of  species  are  grown  for  ornamental  pur- 
poses. N.  tabacum  (tobacco)  is  the  only  one  of  great  commer- 
cial importance. 

NICOTIANA  TABACUM  (Tobacco) 

Habit,  Roots,  Stems. — The  common  tobacco  is  a  strong 
annual  plant,  3  to  5  feet  tall.  The  root  system  is  quite  ex- 
tensive and  fibrous.  The  American  varieties  bear  large, 
thick  stems  which  are  hairy  and  sticky.  In  tobacco  culture 
it  is  customary  to  "top"  the  plants,  that  is,  remove  the 
flower  stalks,  so  that  a  considerable  portion  of  the  food  supply 
which  would  normally  go  to  flower  and  fruit  production  may 
be  directed  to  leaf  growth.  Topping  stimulates  the  produc- 
tion of  "suckers"  (new  shoots).  They  must  be  removed 
before  reaching  any  great  size,  as  the  quahty  of  the  leaves  is 
damaged  by  their  growth.  The  "one-sucker"  type  of 
tobacco  is  one  that  throws  out  one  or  only  a  few  suckers. 

Leaves. — There  is  great  variation  in  the  shape,  color,  tex- 
ture, and  number  of  leaves.  In  cigar-wrapper  tobaccos,  the 
leaves  are  thin,  fine  in  texture,  and  small-veined.  The 
leaves  of  plug  and  pipe  tobaccos  are  usually  coarser,  thicker, 
and  tougher.  The  leaves  are  sessile,  decurrent,  and  either 
narrow  or  broad,  most  commonly  lanceolate  or  ovate,  and 
pointed.  The  number  of  leaves  on  a  plant,  which  is,  of 
course,  important  commercially,  is  different  in  the  various 
types  and  also  varies  considerably  from  plant  to  plant  in  the 


598  BOTANY  or  CROP  PLANTS 

same  type.  In  the  Sumatra  cigar-wrapper  tobacco  the 
leaves  range  from  i6  to  30,  in  the  White  Burley  plug  tobacco 
from  10  to  18,  and  in  the  Zimmer  Spanish  cigar-filler  tobacco 
from  14  to  20. 

Tobacco  plants  are  sometimes  grown  in  the  shade  of  tents, 
which  condition  makes  a  larger  and  thinner  leaf  with  less 
vascular  tissue.  The  leaf  is  thus  improved  for  wrapper 
purposes.  The  chief  effect  of  shade  is  to  reduce  the  rate  of 
transpiration.  There  is  evidence  that  transpiration  rate  is 
the  important  factor  determining  the  development  of  vas- 
cular tissue. 

^' Grain''  in  Tobacco  Leaves. — "Grain"  of  tobacco  appears 
as  small  pimple-like  projections  or  papillae  over  the  cured 
leaf.  The  papillae  vary  in  size  from  about  i  millimeter  to 
microscopic  dimensions.  Each  grain  body  consists  of  from 
one  to  several  leaf  cells  filled  with  crystalline  substance. 
The  grain  is  composed  chiefly  of  calcium,  with  some  potas- 
sium and  magnesium,  in  combination  with  citric  and  maUc 
acids.  Grain  of  tobacco  is  developed  during  the  process  of 
curing  and  fermentation.  It  is  a  character  that  the  buyer 
takes  into  consideration  when  he  selects  tobacco. 

Inflorescence  and  Flowers. — The  inflorescence  is  a  terminal 
panicle.  The  flowers  (Fig.  244)  are  about  2  inches  long,  and 
pink,  yellow,  purple  or  white.  The  tubular  or  bell-shaped 
calyx  is  four-  to  five-cleft.  The  tube  of  the  corolla  is  swollen, 
its  lobes  spreading  and  pointed. 

Pollination  and  Fertilization.^ — Tobacco  flowers  bear  nec- 
taries and  are  visited  by  insects.  Hence,  cross-pollination 
is  probably  somewhat  frequent.  Moreover,  observations 
and  experiments  show  that  the  flowers  are  self-fertile — that 
they  will  produce  viable  seed  when  close-fertilized.  The 
earlier  blossoms  of  an  inflorescence  are  more  commonly 
close-fertilized  than  are  the  later  ones  of  the  same  inflores- 


SOLANACE^ 


599 


cence.  That  the  tobacco  plant  is,  in  all  probability,  natu- 
rally close-fertilized,  is  borne  out  by  the  fact  that  self-fertili- 
zation (inbreeding)  under  control  has  not  resulted  in  a  loss 
of  vigor. 


Fig.  244.— Tobacco  (Nicotiana  tabacum).  A,  flower;  B,  pistil;  C,  corolla 
cut  open  and  spread  out  flat;  D,  cross-section  of  young  fruit;  E,  lengthwise 
section  of  young  fruit.      {After  Slrasbiirger.) 

Fruit.^ — The  fruit  (Fig.  244)  is  a  two-  to  four-valved  cap- 
sule, bearing  numerous  small  seeds.  A  single  plant  may 
produce  as  many  as  a  million  seeds. 

Geographical. — This  species  is  indigenous  to  tropical  South  America.  Its 
varieties  are  now  in  cultivation  throughout  subtropical  and  even  temperate 
climates.  It  occasionally  escapes  from  cultivation  and  runs  wild.  It  is 
grown  commercially  only  in  the  humid  sections  of  this  country. 


6oO  BOTANY  OF  CROP  PLANTS 

Closely  Related  Species. — There  are  a  number  of  species  of  Nicotiana  which 
resemble  N.  tahacum  somewhat,  and  there  are  several  species  belonging  to 
other  genera  besides  Nicotiana  that  go  by  the  name  "tobacco." 

N.  ruslica  is  a  "wild  tobacco"  that  was  cultivated  by  the  Indians.  It  is  a 
tall  annual  with  petioled  leaves.  N.  quadrivalvis  is  another  plant  cultivated 
by  the  Indians  for  tobacco.  It  is  native  to  the  region  extending  from  Texas 
to  California  and  Oregon.  N.  persica  yields  Persian  tobacco.  "Australian 
tobacco"  is  the  leaf  of  Duboisia  hopwoddii,  a  species  of  Solanacea.  "Indian" 
or  "wild  tobacco"  is  a  name  often  given  to  Lobelia  inflata,  the  dried  leaves 
and  tops  of  which  are  officinal.  It  is  a  member  of  the  bellflower  family, 
CampanulacecB.  Arnica  alpina,  a  composite,  is  sometimes  known  as  "moun- 
tain tobacco."  The  most  popular  ornamental  Nicotiana  is  N.  alata.  In  it 
the  flowers  are  white,  open  at  night  and  closed  in  the  daytime. 

Types  arid  Varieties. — There  are  two  general  types  of 
tobacco  grown  in  this  country: 

1.  Cigar  type,  the  leaves  of  which  are  made  into  cigar 
wrappers,  binders  and  fillers.  The  leaves  are  thin  and  of 
fine  texture.  Common  varieties  are  Sumatra,  Connecticut 
Havana,  Connecticut  Broadleaf,  Cuban,  Zimmer  Spanish, 
and  Little  Dutch. 

2.  Export  and  manufacturing  type,  the  leaves  of  which  are 
used  to  make  smoking  tobacco,  chewing  tobacco,  cigarettes, 
and  snuff.  The  leaves,  as  compared  with  those  of  the  pre- 
ceding type,  are  thicker,  tougher,  and  of  coarser  texture. 
Popular  varieties  are  White  Burley,  North  Carolina  Bright 
Yellow,  Maryland  Smoking,  Yellow  Mammoth,  Pryors  and 
Orinocos.  Export  and  manufacturing  tobaccos  are  pro- 
duced on  soils  and  in  sections  of  the  country  different  from 
the  cigar  types.  The  physical  and  chemical  properties  of 
the  soil  have  a  marked  influence  on  the  quality  of  the 
tobacco  leaf.  Light,  well-drained  soils,  in  which  there  is  not 
too  much  organic  matter,  produce  a  leaf  of  mild  flavor  and 
fine  texture.  On  the  other  hand,  heavy,  rich  soils  produce 
a  leaf  of  stronger  flavor  and  coarser  texture. 

Composition. — The  tobacco  plant  is  a  heavy  feeder.     It 


SOLANACE^  6oi 

removes  large  quantities  of  nitrogen,  potash,  and  phosphoric 
acid  from  the  soil.  Consequently,  the  plant  is  rich  in  these 
valuable  plant  nutrients.  In  fact  the  leaves  and  stalks 
make  excellent  fertihzers,  and  are  so  used  in  tobacco  sections. 
Curing  Tobacco. — This  process  consists  in  removing  the 
moisture  in  the  leaves  and  stems  in  such  a  manner  as  to 
produce  a  uniform  color  and  texture  in  the  leaves.  Artificial 
heat  was  first  employed  in  the  curing  of  tobaccos  in  1812. 
Wood  fires  were  used  up  to  the  year  1828,  about  which  time, 
flues,  and  charcoal  fires  came  into  use.  Flue-curing  entirely 
replaced  charcoal  fires  in  1865.  Flue-curing  produces  a 
bright  yellow  leaf.  The  green  tint  is  obtained  by  harvesting 
the  leaf  before  it  is  fully  ripe.  The  dark  export  tobaccos  are 
cured  with  open  hard-wood  fires.  Light  tobaccos  may  be 
air-cured,  and  such  are  used  for  pipe  smoking,  and  cigarettes. 
White  Burley  tobacco,  so  highly  prized  for  twist  and  plug 
chewing  tobaccos,  is  usually  air-cured.  The  yellow  and 
mahogany  tobaccos  are  cured  by  flues.  The  process  takes 
about  four  days.  The  broad  leaf  and  Havana  seed  leaf 
varieties  of  the  Connecticut  Valley  are  air-cured.  They  are 
domestic  cigar'  tobaccos.  Curing  is  often  carried  on  in 
specially  constructed  barns  with  horizontal  ventilators.  It 
usually  takes  about  two  months  to  air-cure  tobacco,  and 
less  time  if  artificial  heat  is  used.  After  the  leaves  have  been 
left  hanging  for  a  long  time,  they  are  packed  closely  in  boxes, 
where  they  are  left  undisturbed  for  several  months.  When 
warm  weather  sets  in,  a  process  of  fermentation  is  set  up  in 
the  cases,  during  which  process  certain  important  changes 
take  place.  Fermentation  may  be  brought  about  after  a 
shorter  period  of  drying  than  is  used  in  the  preceding 
method,  by  placing  the  leaves  in  piles  in  a  warm,  moist  at- 
mosphere. When  the  temperature  reaches  125°  to  i3o°F., 
the  piles  are  opened  and  heaped  up  again.     The  piles  are 


6o2 


BOTANY  OF  CROP  PLANTS 


thrown  down  and  remade  a  number  of  times,  until  the 
leaves  are  ready  for  the  market.  During  the  fermentation 
the  leaf  undergoes  a  number  of  changes  such  as  a  decrease  in 
nicotin,  an  increase  in  alkaline  reaction,  in  ammonia,  and 
nitrate,  a  loss  of  water  and  sugar,  and  a  change  in  the  texture, 
color  and  flavor.  It  is  not  known  positively  whether  fer- 
mentation is  a  result  of  oxidation  by  free  oxygen  of  the  air, 
or  of  bacterial  activity,  or  is  due  to  the  action  of  enzymes. 

The  Tobacco  Industry. — From  colonial  days  the  tobacco 
industry  has  been  an  important  one  in  this  country.  It  is 
interesting  to  note  that  tobacco  was  made  legal  tender  in 
1732  in  Maryland,  where  a  pound  was  i  penny,  and  where  it 
was  used  for  the  "payment  of  all  debts,  including  customs, 
dues,  salaries  of  State  officers  and  ministers  of  the  gospel." 
In  1777  the  tax  levy  for  the  county  and  city  of  Baltimore  was 
172  pounds  of  tobacco  per  poll. 

Virginia  and  Maryland  were  long  the  only  tobacco-pro- 
ducing States.  The  industry  has  now  spread  to  other  States, 
and  the  production  in  191 5  is  shown  in  the  following  table : 

Tobacco:   Acreage,  Production,  and  Total  Farm  Value, 
by'States,  1915 


Kentucky 

North  Carolina. 

Virginia 

Ohio 

Tennessee 

Pennsylvania. . . 
South  Carolina. . 

Wisconsin 

Connecticut 

Maryland 

All  other  States 
United  States... 


Farm    valu 
Dec.  I, 
dollars 


440,000 

320,000 

192,500 

93,700 

92,900 

31,400 

65,000 

41,000 

22,200 

22,000 

47,700 

1,368,400 


356,400,000 

198,400,000 

144,375,000 

84,330,000 

69,675,000 

42,390,000 

37,700,000 

36,900,000 

29,907,000 

16,280,000 

44,030,000 

1,060,387,000 


23,799,000 

22,221,000 

13,571,000 

7,590,000 

4,990,000 

3,900,000 

2,639,000 

2,214,000 

3,095,000 

1,384,000 

12,638,000 

96,041,000 


/v 

T 

ts 

iipiiiHiiiiiiisiii 

T§ 

^X 

^ 

^ 

I: 

|§aS!S?;?:!2"H  =  ="SJ^"""'"- 

i 

c  > 

<^Sv* 

ii 

ji 

SiSSigSisslsKSlSSSHi 

i 

^ — --^^^ 

\    \\^ 

8 

S5sss5sssn:fs«"'"~--   - 

'§ 

EPRESENTS 
ORES' 

VERED    BY  THE 
AS    GREAT    AS 
T   REPRESENTS 

ff^ 

^ 

1 

i^JlJJ^::isiSjJid£i=IJ 

d 

A 

>x       .^^' 

«<  83; 

\  \       \             t^ 

X^"^» 

(      J'-^-^r^         5?r 

t-  o    <  1  a 

V  Y^xj            \ 

'f     y        7     .-^^-^ 

OS  S^-*         / 

1         X                          c — ^ 

\         /                                J 

G°    <^%          / 

V           V    V 

\  \y        r 

-1  w  a           C 

\  \                  c 

'"^'P*'-^) 

iS      ^2f      1 

-^    ^_ig^ 

»     1 

V-^    1? 

^jl''^' 

.  1        ^ 

^^^~"^^J—— 

1 

1 

t 

11-^  « 

i^  1             (               } 

¥^                                         ^^V?                             1 

—   *               »           n.  C       / 

I^           1                                        .^^>-S?    J 

o'fA 

><^_  r^ 

^    o                          t\         \  J 

^■v<~i 

r^  ^-^  1         J 

—  2             \  -^ 

■■■■>.:<'       '>'*>_ 

^ 

ii.  r- 

o 

/ 

LJ 

«  a  2          ) 

o 

1 

r~          A 

si  2    J 

*" 

f^J 

-^. — / -^ 

"1 

Pi^ 

■  %^ 

\                \ 

IS 

^>  ]       V? 

C3  o  q: 

r   ° 

/                           -1 

'i'i 

OC 

»;j      ,       .     y  II 

vi  a 

WmUJm-'    m^i6.                   y-^ 

Q.     Z 

aK*"^  '"'^P'      ^MgaF                      /^ 

g< 

2 

.i? 

r          ^       /-^ 

z 

"•! 

S       a-             **•'               y^ 

si 

1 — ' 

1      '            / 

C3     O                         J 

J                                       / 

• 

"     -                     / 

1 

C3    U.                   1 

1 

."?'                             S 

»-    <                  / 

1 

•                   •           / 

~                 / 

/       L 

J 

i^ 

N          / 

{~~~U~~ 

-f 

— — Jj| 

\l 

fSSs 

% 

i: 

«          /                                    ^ 

r*                / 

/ 

/  o 

UJ 

M 

/       ~^^' —     / 

-J^ 

-i. 

/.■a               S 

h- 

te 

Jlii 

it 

3 

p 

i^5sga§s^ 

h^  j\ 

J^. 

5 

i^JJ^iiiJ 

"-—A^-*. . 

..v^.-- 

ii 

llllllll 

JI.770 
12,023 
8,391 
2,433 

'^^\_ 



B- 

||i|iiddJI. 

I 

-^-x^U>^ 

" 

\ 

M^ 

6o4  BOTANY  OF  CROP  PLANTS 

The  United  States  leads  all  other  countries  in  the  produc- 
tion of  tobacco.  In  19 14,  Japan  ranked  second  to  the 
United  States,  but  its  output  was  only  about  10  per  cent,  of 
that  in  this  country. 

References 

Appleman,   C.   O.:  Physiological  Behavior  of  Enzymes  and  Carbohydrate 

Transformations  in  After-ripening  of  the  Potato  Tuber.     Bot.  Gaz.,  52: 

306-31S,  1911. 
Barnes,  J.:  The  Potato  (Solanum  Tuberosum):  Its  History,  Microscopical 

Characters,  and  Structure.     Ann.  Rep.  Trans.  North  Staffordshire  Field, 

cl,  1902-03,  pp.  96-106. 
Bernard,  Noel:  Sur  la  tuberculization  de  la  pomme  de  terre.     Compt. 

Rend.  Acad.  Sci.  (Paris),  132:  355-357,  iQoi- 
Berthault,  Pierre:  Recherches  botaniques  sur  les  varieties  cultivees  du 

Solanum  tuberosum  et  les  especes  sauvages  de  Solanum  tuberiferes  voisins. 

Ann.  Sci.  Agron.,  28:  1-59,  87-143,  173-216,  248-291,  Paris,  191 1. 
Fitch,   C.  L.:  Productiveness  and  Degeneracy  of  the  Irish  Potato.     Colo. 

Agr.  Exp.  Sta.  Bull.  176:  1-16,  1910. 
Indentification  of  Potato  Varieties.     la.  Agr.  Ext.  Dept.  Bull.  20: 1-32, 

194. 
Fletcher,  S.  W.,  and  Gregg,  O.  I.:  Pollination  of  Forced  Tomatoes.     Mich. 

Agr.  Exp.  Sta.  Spec.  Bull.  39:  2-10,  1907. 
Pollination  of  Forced  Tomatoes.     Mich.  Agr.  Exp.  Sta.  Spec.  Bull.  39: 

294-301,  1907. 
Gable,  C.  H.:  The  Wild  Tomato.     Jour.  Hered.,  6:  242,  1915. 
Gilmore,  John  W.:  Quality  in  Potatoes.     Cornell  Agr.  Exp.  Sta.  Bull.  230: 

503-525,  1905. 
GooDSPEED,  T.  H.:  Parthenogenesis,  Parthenocarpy  and  Phenospermy  in 

Nicotiana.     Univ.  Calif.  Pub.  Bot.,  5:  249-272,  1915. 
Halstead,  B.  B.:  Notes  upon  Stamens  of  Solanaceae.     Bot.  Gaz.,  15:  103- 

106,  1890. 
Meckel,  E.:  Sur  I'origine  de  la  pomme  de  terre  cultivee  et  sur  les  mutations 

gemmaires  culturales  des  Solanum  tuberiferes  sauvages.     Ann.  Fac.  Sc. 

Marseille,  1907,  82  pp. 
Irish,  H.  C:  A  Revision  of  the  Genus  Capsicum  with  Especial  Reference  to 

Garden  Varieties.     9th  Ann.  Rep.  Mo.  Bot.  Card.,  53-110,  1898. 
Jones,  Donald  F.:  Natural  Cross-pollination  in  the  Tomato.    Science,  n.  s., 

43:  509-510,  1916. 
Klemt,  F.:  t)ber  den  Bau  und  die  Entwickelung  der  Solanaceenfruchte. 

Berlin,  1907. 


SOLANACE^  605 

Magrou,  H.:  Symbiosis  and  Tuberizatioa  in  Potato.     Compt.  Rend.  Acad. 

Sci.  (Paris),  158:  50-53,  1914. 
MiDDLETON,  R.  Morton:  Solanum  Tuberosum  L.,  and  Its. Allies.     Jour. 

Bot.,  47:  228,  1Q09. 
Reed,  T.:  Tbe  Anatomy  of  Some  Tubers.     Ann.  Bot.,  24:  537-548,  1910 

(Potato  and  Jerusalem  artichoke). 
Rendle,  a.  B.:  Production  of  Tubers  within  the  Potato.     Jour.  Bot.,  31: 

193-19S,  1893. 
Rigdway,  Charles  S.:  Grain  of  the  Tobacco  Leaf .     Journ.  Agri.  Research, 

7:  269-288,  1916. 
Stewart,    F.    C:   Observation  on  Some  Degenerate  Strains  of  Potatoes. 

N.  Y.  Agr.  Exp.  Sta.  Bull.  422:  319-357,  1916. 
Stuart,  William:  Group  Classification  and  Varietal  Descriptions  of  Some 

American  Potatoes.     U.  S.  Dept.  Agr.  Bull.  176:  1-56,  1915. 
WiTTMACK,  L.:  Die  Stammpflanze  unserer  Kartoffel.    Landw.  Jahrb.,  38: 

551-605,  1909. 
Studien  iiber  die  Stammpflanze  der  Kartoffel.     Ber.  Bot.  Gesell.,  27:  28- 

42,  1909. 


CHAPTER  XXXIX 
CUCURBITACEiE  (Gourd  Family) 

There  are  about  650  species  of  cucurbits,  mainly  in  tropical 
regions.  All  cultivated  cucurbits  are  easily  injured  by 
frost,  and  are  distinctly  warm  season  crops. 

A  number  of  species  are  of  economic  importance.  Chief  of 
these  are  the  pumpkin,  squash,  watermelon,  muskmelon,  and 
cucumber.  The  wild  cucumber  [Echinocystis  lohata)  and 
the  star  cucumber  {Sicyos  angulatus)  are  sometimes  planted 
as  ornamental  vines.  The  squirting  cucumber  {Echallium 
elaterium)  is  a  fleshy  herb  containing  a  cathartic  and  poison- 
ous principle,  elaterin,  the  main  ingredient  of  elaterium. 

H'.abit.— The  members  of  this  family  are  commonly  known 
as  "cucurbits."  The  majority  of  them  are  annual,  climbing 
or  trailing  herbs,  with  tendrils,  but  often  reaching  a  large 
size. 

Steins  and  Leaves. — The  stems  are  hollow  and  usually 
covered  with  stiff  hairs.  The  leaves  are  large,  alternate, 
petioled,  heart-shaped,  palmately  lobed  or  dissected.  The 
tendrils  arise  as  a  rule  in  the  axils  of  leaves.  The  same  ten- 
dril may  be  dextrorse  and  sinistrorse  at  different  points  along 
its  axis  and  may  be  simple  or  forked. 

Flowers. — The  flowers  (Figs.  246  and  247)  are  axillary, 
either  solitary,  paniculate,  or  rarely  racemose  or  subumbel- 
late.  They  are  monoecious  or  dioecious,  commonly  white  or 
yellow,  rarely  blue  or  red.  The  calyx  forms  a  tube  which  is 
adnate  to  the  inferior  ovary;  its  limb  is  tubular  or  campanu- 
606 


CUCUIU3ITACE/E 


6o7 


late,  and  usuall\'  has  il\e  iml)ricate(l  lobes.  The  corolla  is  hve- 
lobed,  usually  sympetalous,  sometimes  parted  to  the  base,  in- 
serted on  the  limb  of  the  calyx,  and  rotate  or  campanulate. 
The  stamens  (Fig.  247)  are  five  in  number,  hut  they  often  grow 


Fig.   246. — -Field  pumpkin  (.Cucurbita  pepo). 
late  flower. 


staminate  flower;  B,  pistil- 


together  so  that  there  are  apparently  three.  In  case  there 
are  three  stamens,  two  of  them  are  broader  than  the  third; 
the  two  broad  stamens  have  two-celled  anthers,  the  other  has 
a  one-celled  anther,  thus  makinii;  in  all  Uvv  anther  cells  to  tln' 
andrcecium.     The    lilaments   are    short,    often    united,    and 


6o8 


BOTANY  OF   CROP  PLANTS 


tipped  by  the  worm-like  pollen  sacs.     The  ovary  (Fig.  248)  is 
inferior,  one-  to  three-celled,  and  usually  has  numerous  seeds 
in  each  cell  or  locule;  the  style  is  terminal,  simple  or  lobed. 
Fruit.     The  />////  is  a  jK'po.  usually  indchiscent,  or  in  some 


Fic.  247. — Field  pumpkin  (Cucurl)il;i  p 
iKito  llciwcr;  hoth  will 


flower;    /5.  si  aini- 


cases  (M icniDi pelts.  Cytiautlicra)  dehiscent  at  the  apex  or 
bursling  irre.L,ailarl\-.  In  many  instances  (watermelon, 
I)umpkin.  s(|uash).  llu-  Iruit  is  of  enormous  si/e.  The  outer 
pari  (»r  the  fruit  is  reie[)lacle  which  has  biHome  altatlu-d  to 
the  exocarp.     Tht-  th-sh  of  the  frnit  i>  chirll_\-  mcsotarj)  and 


CUCURBITACE/E 


609 


Fig.    248. — Cross-scclinii   ci     niaiunj   I'ruil    of  cucumber    (Cucumis   sativus). 


Fk;.  249.  —  (;.i'niiinati.,u  , ,(  pumpkin  1  Hi;,'  Tmhu  .,_■,■, i,.'  ,h..\vinK'  llu' 
pegs  functioning  in  the  removal  of  the  co;its.  (AjUr  Crocker.  Knighl  and 
Roberts.) 


39 


6 10  BOTANY  or  CROP  PLANTS 

endocarp.     Seeds  are  usually  abundant,  ilat.  and  without 
endosperm. 

Germination  of  Cucurbit  Seeds.  -The  cotyle(K)ns  are 
epigean  in  all  the  common  members  of  the  Cucurbitaceie. 
There  are  a  few  hypogean  forms,  such  as  MegarJiiza  calif oniica 
and  Sicyospeyma  gracUis.  The  first  portion  of  the  seedling  to 
appear  above  ground  is  the  hypocotyl,  which  emerges  as  an 
arch  (Fig.  249).  At  the  base  of  the  hypocotyledonar\-  arch, 
there  is  developed  a  peculiar  outgrowth  known  as  the  "  prg.'^ 
It  is  a  natural  part  of  the  plant,  and  although  it  \arics  some- 
what in  size  in  dilTerent  cucurbits,  it  has  been  shown  that 
gra\ity  has  no  direct  effect  in  increasing  peg  de\el<)[)nient 
or  in  determining  its  lateral  placement  on  the  hyi)()cotyl. 
The  peg  serves  to  hold  the  seed  coat  while  the  hy[)oc()lyl 
withdraws  the  cotyledons  from  the  coat.  It  will  be  noticed 
(Fig.  249)  that  one  edge  of  the  ^cc(.\  coat  is  caught  against  the 

Key  to  Principal  Genera 

C(jrolla  rotate  or  campanulate,  five-parted  to  or  almost  to  the  base. 

Tendrils  often  two  to  three  times  branched,  Cilrulliis  (watermelon,  citron). 

Tendrils  simple,  Cncumis  (muskmelon,  cantaloupe,  cucumber). 
Corolla   campanulate,'  fivc-lobed  to  or  little  below  middle  Ciicurhild  (j,'ourd 

pumpkin,  squash). 

CUCURBITA  (Squash,  Pumpkin,  Gourd) 

Stems,  Leaves,  Flowers. — Members  of  this  genus  arc 
annual,  prostrate  bushy  or  trailing  vines  with  rough  stems 
which  have  a  tendency  to  root  at  the  nodes.  The  tendency  is 
particularly  marked  in  the  long-running  varieties  of  scjuashes 
(Turban,  Marblehead,  Canada  Crookneck,  Field  Pumpkin). 
The  tendrils  are  branched.  The  leaves  are  usually  cordate 
at  the  base,  lobed  (C.  pepo),  or  not  Ujljcd  iC.  ffiaxinia). 
The  jlou'crs  are  alwa}'s  solitary  in  the  a.xils  of  the  lca\es, 
yellow,  and   monoecious.     In  squashes  with  a  bushy  habit 


CUCURBITACE^  6tt 

(early  squashes),  the  staminate  flowers  are  on  long  peduncles, 
while  the  pistillate  flowers  occur  near  the  base  of  the  plant 
on  comparatively  short  peduncles.  In  the  long-running 
squashes  (fall  and  winter  types),  the  staminate  flowers  are 
borne  near  the  center  of  the  plant  on  long  peduncles,  while 
the  pistillate  occur  some  distance  from  the  roots,  on  compara- 
tively short  stalks.  The  flower  stalks  (peduncles)  may  be 
strongly  ridged  (as  in  C  pepo  and  C.  moschata)  or  compara- 
tively smooth  (as  in  C.  maxima) .  In  the  staminate  flowers,  the 
calyx  tube  and  corolla  are  campanulate  and  five-lobed;  the 
stamens  are  three  in  number,  inserted  on  the  calyx  tube,  the 
filaments  are  free,  and  the  anthers  large,  linear,  and  more 
or  less  united;  the  ovary  is  rudimentary.  In  the  pistillate 
flowers,  the  calyx  and  corolla  are  as  described  above;  the 
stamens  are  rudimentary  (three  staminodia  commonly 
present),  pistil  one,  ovary  oblong  with  three  to  five  many- 
ovuled  placentae,  style  short  and  thick,  and  stigmas  three  to 
five,  each  two-lobed  and  papillose.  There  are  always  many 
more  staminate  flowers  produced  than  pistiflate. 

Pollination  and  Fertilization. — The  squashes  and  pump- 
kins are  usually  insect-pollinated.  It  has  been  shown  that 
the  varieties  of  C  pepo,  including  the  common  Crookneck, 
Scallop,  and  Pineapple  squashes,  and  the  common  field 
pumpkin,  will  readily  cross  with  one  another.  However,  the 
above  will  not  cross  with  varieties  of  C.  maxima,  including 
Hubbard,  Marblehead,  Turbans,  and  Mammoth  Chili  and 
Valparaiso  pumpkins.  These  latter  will  cross  with  one 
another.  Varieties  of  C.  moschata  will  not  cross  with  either 
of  the  above  species.  Cucurbita  species  do  not  cross  with 
melons  and  cucumbers.  Squashes  and  pumpkins  ordinarily 
do  not  reach  any  considerable  size  unless  the  ovules  are 
fertilized. 

Mature   Fruit.- — The    mature    fruit   is    a  pepo.     In  the 


6l2 


BOTANY  OF  CROP  PLANTS 


Turban  squashes,  the  receptacle  does  not  extend  over  the 
top  of  the  ovary,  while  in  most  other  sorts,  it  is  entirely 
closed  at  the  top.     The  pericarp  is  fleshy. 


Fig.  250. — A,  cross-section  of  squash  (Cucurbita   maxima)  fruit  stalk;  B, 
same  of  pumpkin  (Cucurbita  pepo). 

Geographical. — The  genus  Cucurbita  has  about  10  species,  natives  of  trop- 
ical America,  Asia,  and  Africa. 


Key  to  Important  Species  of  Cucurbita 

Leaves  lobed;  stalks  of  fruit  strongly  ridged  (Fig.  250,  B). 

Calyx  lobes  narrow,  peduncle  not  enlarged  next  to  the  fruit  (Fig.  251,  B) 


Fig.  251. 


-A,  fruit  stalk  of  Cucurbita  maxima;  B,  of  C.  pepo;  C,  of  C.  mos- 
chata.     {After  Bailey.) 


Cucurbita  pepo  (pumpkin,  scallop,  gourd). 
Calyx  lobes  broad,  peduncle  much  enlarged  next  to  the  fruit  (Fig.  251,  C), 
C.  moschata  (Canada  Crookneck  and  Cushaw). 
Leaves  not  lobed;  stalks  of  fruit  not  prominently  ridged  (Fig.  250,  A),  Cucur- 
bita maxima  (Marblehead,  Turban,  Hubbard  squashes,  etc.). 


CUCURBIT  ACE^  613 

CUCUKBITA  PEPO 

Description. — This  is  an  annual  species,  with  long,  running 
stems;  in  the  so-called  "bush-pumpkins,"  which  include  the 
scallops  (patty-pans  or  cymblings)  and  summer  or  crookneck 
squashes,  the  plants  are  more  compact.  The  leaves  are 
three-  to  five-lobed.  The  calyx  lobes  are  narrow.  The 
peduncle  is  not  enlarged  next  to  the  fruit.  The  fruit  varies 
much  in  size  and  shape. 

Origin. — There  is  a  question  as  to  the  origin  of  the  pump- 
kin. It  is  considered  by  some  to  be  of  American  origin,  as 
it  was  cultivated  by  the  Indians  at  the  time  America  was 
discovered.  However,  it  is  claimed  by  others  that  its  original 
home  is  southern  Asia. 

Types  and  Varieties. — Cucurhita  pepo  includes  the  follow- 
ing groups: 

Plants  with  long,  running  stems,  True  field  pumpkins  (Connecticut  field  and 
Mammoth  are  common  varieties). 
Some  of  the  vegetable  marrows  have  long,  running  stems,  while  others 
have  a  bushy  habit.     As  a  group  they  are  relatively  unimportant. 

Plants  bushy,  Summer  squashes,  crooknecks.  In  these  the  neck  is  decidedly 
crooked  and  narrow,  the  distal  end  is  swollen  but  terminating  in  a  point, 
the  skin  is  orange-colored  and  covered  with  many  round  excrescences. 
Scallop  or  pally-pan  varieties.  These  are  also  known  as  custard  marrows, 
and  in  the  South  as  cymblings.  The  leaves  are  large,  entire,  and  very 
slightly  five-lobed;  the  fruit  is  much  broader  than  long,  the  edge  coarsely 
scalloped;  the  flesh  is  solid  and  floury;  the  skin  is  smooth  and  of  various 
colors.     The  pineapple  summer  squashes  are  oblong-conical  varieties. 

Plants  with  slender,  running  stems;  leaves  lobed;  fruit  small,  hard,  not  edible, 
of  various  shapes.  Gourds  (in  part)  (C.  pepo  var.  ovifera). 


Not  all  "gourds"  belong  to  the  species  Cucurhita  pepo. 
In  addition  to  this  species,  they  are  also  referred  to  Lagenaria 
vulgaris,  Lufa,  Cucumis  dipsaceus,  Cucumis  anguria,  and 
Benincasa  c&rifera. 


6l4  BOTANY  OF  CEOP  PLANTS 

CUCURBITA  MAXIMA 

Description. — This  is  an  annual  plant  with  long,  running, 
cylindrical,  somewhat  prickly  (not  spiny)  and  hairy  stems. 
The  leaves  are  large,  not  lobed,  except  on  young  shoots.  The 
peduncles  are  smooth,  i.e.,  not  ridged.  The  calyx  tube  is 
not  ribbed.  The  corolla  tube  is  of  equal  diameter  through- 
out, the  lobes  curved  outward.  The  fruit  varies  in  shape 
and  size,  but  unlike  representatives  of  the  preceding  species, 
it  never  has  a  light  color  or  a  crookneck  or  bears  warty  ex- 
crescences; the  peduncle  is  not  much  enlarged  next  to  the 
fruit. 

It  is  quite  agreed  that  this  species  is  of  American  origin. 

Type  and  Varieties.- — Representatives  of  the  species  C. 
maxima  are  late  maturing,  as  a  rule,  and  hence  are  quite 
generally  known  as  "winter  squashes."  The  principal  types 
are  as  follows: 

1.  Turban  Squashes. — The  fruit  has  the  appearance  of  a 
turban  or  "Turk's-cap."  This  is  due  to  the  failure  of  the 
fleshy  receptacle  to  completely  cover  over  the  ovary,  and 
hence  the  latter  protrudes,  forming  a  fruit  the  character  of 
which  suggests  the  expression  "squash  within  squash." 

2.  Hubbard  Squashes. — These  are  the  mo^t  popular 
squashes  in  the  Northern  States.  They  are  broadly  pear- 
shaped,  or  olive-shaped  with  very  thick,  hard,  dark  green 
skin  and  dark  yellow,  floury  flesh.  There  are  varieties  of 
the  Hubbard  (Red  or  Golden  Hubbard)  with  orange-red  skin. 

3.  Marblehead  Squashes. — These  have  a  gray  skin.  Other- 
wise they  resemble  the  Hubbard  squashes. 

4.  Marrow  Squashes. — There  are  a  number  of  varieties  of 
these,  only  a  few  of  which  are  very  well  known.  Most  of 
them  have  a  smooth  skin  and  a  very  floury  flesh.  The 
Boston  Marrow,  a  variety  with  orange-colored  skin  and  flesh, 
is  the  best  known  in  the  United  States. 


CUCUEBITACE^  615 

5.  Mammoth  Pumpkins  and  Squashes. — These  are  the 
largest  of  the  squashes.  Some  varieties  (Mammoth  Whale 
squash,  Valparaiso  squash,  Mammoth  pumpkin)  attain  a 
diameter  of  i  to  2  feet  and  a  weight  of  100  to  200  pounds. 
The  Mammoth  pumpkins  are  strongly  flattened  at  the  ends, 
while  the  mammoth  squashes  are  longer  than  broad,  and 
oblong  or  narrowly  oval  in  shape. 

CUCURBITA  MOSCHATA 

Description. — This  is  an  annual  with  long,  running,  hairy 
(never  spiny)  stems  which  readily  root  at  the  nodes.  The 
leaves  are  lobed,  dark  green  and  with  whitish  blotches  here 
and  there.  It  is  said  that  these  whitish  areas  are  due  to  a 
thin  layer  of  air  beneath  the  epidermis.  The  calyx  is  deeply 
lobed.  The  corolla  widens  upward.  The  peduncle  is 
angular,  deeply  ridged,  and  swollen  where  it  joins  the  fruit. 
The  flesh  of  the  fruii  usually  has  a  musky  flavor. 

The  species  is  said  to  have  originated  in  Eastern  Asia. 

Types. — The  principal  types  belonging  to  this  species  are: 

1.  Canada  Crookneck  or  Winter  Gourd. — The  plants  are 
small;  the  fruit  is  also  rather  small,  smooth  and  crook- 
necked.        • 

2.  Cushaw. — This  is  the  "pie  pumpkin"  or  squash  of  the 
South  and  Southwest.  It  is  a  crook-necked  type  of  squash, 
the  skin  of  which  may  be  white,  yellow,  or  striped. 

CUCUMIS  (Muskmelon,  Cantaloupe,  Cucvimber) 

Stems,  Leaves,  Flowers. — All  of  our  common  species  are 
hispid  or  rough,  trailing,  annual  herbs.  The  tendrils  are 
simple.  The  leaves  are  simple,  palmately  three-  to  five-lobed 
or  dissected.  The  flowers  are  monoecious.  Rane  finds  that 
some  varieties  of  muskmelons  possess  perfect  flowers.     For 


6l6 


BOTANY   OF  CROP   PLANTS 


example,    out   of   95    varieties    examined,    85    had   perfect 
flowers,  and  only  1 1  had  imperfect  flowers. 

The  staminate  flowers  are  in  small  clusters,  or  rarely  soli- 
tary. The  calyx  tube  is  turbinate  or  campanulate,  and  its 
limb  five-lobed.  The  corolla  is  campanulate,  deeply  five- 
lobed  or  five-parted,  the  lobes  acute.     The  three  stamens  are 


Fig.  252. — Leaves  of  A,  cucumber    (Cucumis  sativus)  and  B.    muskmelon 
(Cucumis  melo).      X  M. 


separate,  with  short  filaments  and  oblong  anthers.  The 
ovary  is  rudimentary. 

Pistillate  flowers  are  solitary.  The  calyx  and  corolla  are 
similar  to  those  described  above.  The  ovary  is  ovoid  or 
globose,  with  three  to  five  placentae;  the  style  is  single  and 
short,  the  stigmas  obtuse,  three  in  number,  and  the  ovules 
numerous.  The  fruit  is  a  pepo  varying  in  shape,  size,  sur- 
face characters,  and  physical  and  chemical  composition. 

Pollination. — Grifhn  gives  data  with  reference  to  pollina- 
tion and  fruiting  of  the  cantaloupe.     He  kept  an  account  of 


CUCURBITACEiE  617 

the  number  of  flowers  produced  on  each  of  six  vines,  from 
June  27  to  July  13,  at  which  latter  date  the  vines  became 
indistinguishable  from  each  other.     His  data  are  as  follows: 

Number  of   flowers 
Date  Staminate  Pistillate 

June  27 203  I 

June  30 338  II 

July    3 474  28 

July    7 755  95 

July  10 660  87 

July  13 64s  31 

Total 3,075  253 

Average  to  each  vine 512  42 

Vines  continue  to  bloom  profusely  until  late  in  August  in 
the  locality  (Rocky  Ford,  Colorado)  where  data  were  ob- 
tained. Here,  melons  may  ripen  that  are  set  as  late  as  the 
middle  of  August;  it  takes  about  six  weeks  for  one  to  mature. 
Twenty  ripe  melons  per  vine  is  a  good  crop.  In  all  Cucumis 
species,  the  staminate  flowers  are  more  numerous  and  appear 
earHer  than  the  pistillate  ones.  Pollination  is  carried  on  by 
insects.  Ordinarily,  lack  of  fertilization  causes  a  premature 
dropping  of  the  fruit,  and  incomplete  fertiHzation  results  in 
misshapen  fruit. 

Geographical.— There  are  cldse  to  30  species  of  Cucumis,  most  of  them  be- 
longing to  tropical  Asia,  Africa,  and  the  East  Indies. 

Key  to  Principal  Species 

Fruit  smooth,  not  spiny  or  tuberculate  at  maturity,  Cucumis  melo  (musk- 
melon,  cantaloupe,  melons). 
Fruit  spiny  or  tuberculate  at  maturity. 
Stems  (cultivated)  6  to  15  feet  long;  fruit  6  to  12  inches  long,  Cucumis 

sativus  (cucumber). 
Stems  3  to  6  feet  long;  fruit  i  to  i>^  inches  long,  Cucumis  anguria  (prickly 
cucumber.  West  Indian  gherkin,  Jerusalem  cucumber,  gooseberry  gourd). 


6l8  BOTANY  OF  CROP  PLANTS 

CUCUMIS  MELO  (Muskmelon,  Cantaloupe,  Melons) 

Description. — This  is  a  hirsute  or  rough  annual  herb  with 
prostrate  stems.  The  leaves  are  subcordate,  with  somewhat 
rounded  angles.  The  flowers  are  monoecious,  or  in  some 
varieties  the  pistillate  flowers  are  with  stamens.  The  fruit 
varies  in  shape  and  size. 

Cucumis  melo  is  considered  to  be  a  native  of  southern  Asia. 

Botanical  Varieties  of  Cucumis  melo. — Naudin  has  mono- 
graphed the  species  Cucumis  melo,  and  according  to  him,  it 
is  divided  into  a  number  of  botanical  varieties,  races,  or 
groups  which  can  be  fertihzed  by  each  other.  The  principal 
ones  are  as  follows: 

1.  Netted  Melons  {Cucumis  melo  var.  reticulatus) . — To  this 
group  belong  the  common  muskmelons.  These  usually  have 
a  netted  skin,  sometimes  almost  smooth.  All  of  them  are 
shallow  ribbed  melons,  the  flesh  of  which  may  be  green-  or 
salmon-tinted  (Jenny  Lind,  Emerald  Green,  Netted  Gem, 
Rust  Resistant  Pollock,  Ironclad,  Montreal  Nutmeg,  Cos- 
mopolitan, Ryan's  Early  Watters).  The  so-called  "Rocky 
Ford  Cantaloupes"  are  not  true  cantaloupes;  the  "Rocky 
Fords"  include  a  number  of  varieties  (chiefly  Rust  Resistant 
Pollock  No.  25,  Netted  Gem),  all  of  which  are  netted  melons 
(var.  reticulatus). 

2.  Cantaloupes  or  Rockmelons  {Cucumis  melo  var.  canta- 
lupensis)  .—The  true  cantaloupes  are  usually  deep-ribbed, 
hard-rinded,  and  warty  or  scaly.  The  flesh  is  either  green- 
or  salmon-tinted  (Hackensack,  Nutmeg,  Carmes,  Long 
Yellow). 

3.  Pineapple  Melons  {Cucumis  melo  var.  saccharinus) . — 
These  resemble  the  common  netted  melons.  They  are  ob- 
long in  shape  and  have  a  very  tender  flesh. 

4.  Snake  Melon  or  Snake  Cucumber  {Cucumis  melo  var. 
flexuosus). — The  fruit  of  this  is  long  and  slender,  bent  and 


CUCUrtRITACE.E 


619 


twisted,  furrowed,  and  thickest  at   tlu-  distal  end.     It  often 
reaches  a  length  of  3  feet,  and  a  diameter  of  i  to  3  inches. 


Fk;.  25.5.  —  1  to  0,  sUij^us  ill  tli(j  licvolopnient  ot  ihe  cucumber  fruit;  tlx' 
(lower  is  unopen  in  r  and  2,  in  3  it  is  fully  open,  in  4  and  5  it  is  withering,  and 
in  6  the  perianth,  stamens  and  styles  have  fallen  from  the  enlarged  ovary.  7, 
staniinate  flower  of  cucumlier. 


5.   Ulnlcr  Melons   (CiicKmis   mrlo  var.   inodorns).- LiiUc 
known  in  United  States. 


620  BOTANY  OF  CROP  PLANTS 

6.  C IK  umber  Melon  {CuciiDiis  nuio  var.  acidnlns). — Of  no 
economic  importance. 

7.  Orange  Melon.  Maiiii^o  Melon,  }[cloii  Apple,  Vine  Peach, 
Garden  Lemon,  Vegetable  Orange  (Cuciuius  mclo  var.  chito). — 
Used  in  making  preserves. 

8.  Dudaim  Melon,  Pomegranate  Melon,  Queen  Anne's 
Pocket  Melon  {Cucumis  mclo  var.  dudaim). — Inedible. 

CUCUMIS  SATIVUS  (Cucumber) 

Description. — This  is  an  annual  plant  with  rough,  hispid 
stems  which  reach  a  length  of  6  to  15  feet,  and  are  somewhat 
branching.  The  leaves  are  subcordate,  almost  as  wide  as 
long,  and  somewhat  five-lobed.  The  corolla  is  yellow. 
There  is  a  general  impression  that  the  cucumber  can  })e 
crossed  with  the  melon.  Experiments  have  shown  that  this 
crossing  is  impossible.  The  fruit  is  oblong,  obscurely  threc- 
anglcd,  tuberculate  when  young,  but  often  becoming  smooth 
(in  cultivated  forms)  at  maturity. 

Geographical.— Cucumljcrs  have  been  in  cultivation  for  3,000  or  4,000 
years.  Thcj'  were  first  cultivated  in  Asia.  The  species  has  not  been  found 
growing  wild. 

Closely  Related  Forms. — There  are  a  number  of  "cucum- 
bers" which  may  be  confused  (at  least  in  name)  with  the 
common  cucumber  {Cucumis  sativus).  Chief  of  these  are 
the  snake  cucumber  (Cucumis  mclo  var.  flexuosus).  West 
Indian  gherkin  {Cucumis  anguria),  musk  cucumber  {Cucumis 
moschata),  and  star  cucumber  {Sicyos  ungulalus).  The  snake- 
cucumber  is  in  reality  a  melon.  It  is  characterized  b>-  the 
long,  narrow,  twisted  fruit.  In  the  West  Indian  gherkin  the 
stems  are  shorter  and  the  fruit  much  smaller  than  those  of 
the  cucumber.  It  is  a  common  practice  to  use  young  cucum- 
bers as  gherkins.     The  musk  cucumber  is  also  a  melon.     The 


CUCURBIT  ACE^  6  2 1 

star  cucumber  fruit  is  compressed,  dry  and  membranous,  and 
occurs  in  head-like  clusters. 

Types. — There  are  three  principal  types  of  cucumbers 
{Cucumis  sativus):  (i)  Common  field  cucumbers;  (2)  English 
or  forcing  cucumbers  (var.  anglicus);  and  (3)  Sikkim  cucum- 
bers (var.  Sikkimensis) .  The  field  cucumbers  are  divided 
into  black  spine  varieties  and  white  spine  varieties,  and  these 
two  divisions  are  further  subdivided. 

The  English  or  forcing  cucumbers  differ  from  the  ordinary 
cucumbers.  In  the  forcing-house,  the  former  do  not  need 
artificial  fertilization,  while  all  our  common  cucumbers  must 
be  artificially  fertilized.  Hence,  the  English  cucumbers  have 
the  habit  of  producing  seedless  fruit.  The  fruit  "of  the 
forcing  cucumber  is  long  and  smooth,  green  in  color,  and  at 
first  covered  with  a  few  black  spines.  Common  varieties 
are  Telegraph,  Sion  House,  Kenyon,  and  Lome.  The  Sik- 
kim cucumber  fruit  is  large  and  reddish  brown,  marked  with 
yellow. 

Pickles. — The  growing  of  cucumbers  for  pickling  is  an 
industry  quite  different  from  that  having  to  do  with  the 
cultivation  of  cucumbers  for  slicing.  The  pickle  industry  is 
mostly  restricted  to  the  Northern  States,  as  cucumbers  for 
this  industry  do  best  in  the  cooler  climate  of  the  north. 
Cucumbers  that  are  to  be  pickled  are  harvested  before  they 
reach  maturity,  and  are  not  allowed  to  reach  a  length  of 
more  than  about  5-  inches.  They  are  hauled  to  the  local 
"salting  station,"  where  they  are  immersed  in  a  brine,  which 
is  contained  by  large  wooden  tanks,  some  with  a  capacity  of 
1,500  bushels.  The  pickles  are  kept  in  these  tanks  until 
ready  to  be  bottled  at  the  factory. 

Dill  pickles  are  made  either  from  pickles  stored  in  brine 
or  from  fresh  cucumbers  from  the  vine.  The  peculiar 
flavor  of  dill  pickles  is  secured  by  adding  to  the  brine  and 


622  BOTANY  OF  CROP  PLANTS 

cucumbers,  the  stems,  leaves,  flowering  heads,  and  seeds  of 
dill,  and  also,  sometimes,  a  spice  made  from  allspice,  crushed 
black  pepper,  coriander  seed,  and  bay  leaves.  Some 
vinegar  is  added  in  the  later  stages  of  the  pickling  process. 

CUCUMIS  ANGURIA  (Gherkin) 

Description. — This  is  an  annual,  creeping,  branching 
plant.  The  stems  are  slender,  rough-hairy,  and  bear  simple 
tendrils.  The  leaves  are  deeply  sinuate-lobed.  Staminate 
flowers  are  small,  numerous,  and  on  short  peduncles,  while 
pistillate  flowers  are  on  long  stalks.  The  fruit  is  about  ij^^ 
inches  long,  oval,  prickly,  and  green  with  whitish  streaks. 
The  flesh  is  thin,  and  the  seeds  form  a  proportionately  large 
percentage  of  the  fruit. 

The  species  is  native  of  the  West  India  Islands. 

The  genuine  gherkins  of  commerce  are  the  fruit  of  C. 
anguria.  Small  cucumbers  (C.  s ativus)  a,re  often  substituted 
for  them,  however. 

CITRULLUS  (Watermelon,  Citron,  Colocynth) 

Description. — Citrullus  species  are  coarse,  trailing  herbs 
with  branched  tendrils.  The  leaves  are  rotund-cordate,  and 
three-  to  five-lobed.  The  flowers  are  monoecious,  and  always 
solitary.  In  the  staminate  flowers,  the  calyx  has  a  broad 
campanulate  tube  and  a  five-lobed  limb,  and  the  corolla  is 
five-parted  to  below  the  middle;  there  are  three  stamens  with 
subsessile  anthers,  one  of  which  is  one-loculed,  the  other 
two,  two-loculed.  In  the  pistillate  flowers,  the  calyx  and 
corolla  are  as  described  above.  The  ovary  is  ovoid  with 
three  fleshy  placentae;  the  style  is  short,  with  three  large 
stigmas,  and  ovules  are  numerous.  The  fruit  varies  widely 
in  form  and  size,  color  and  thickness  of  skin,  flavor,  etc. 


CUCURBITACE^  623 

Geographical. — There  are  two  or  three  species  of  Citrullus,  natives  of  the 
Mediterranean  region,  Africa,  and  Asia.  The  only  one  of  agricultural  im- 
portance is  Citrullus  vulgaris,  which  includes  the  watermelon  and  citron. 

CITRULLUS  VULGARIS  (Watermelon,  Citron) 

Description. — The  watermelon  is  a  hairy  annual  with 
long,  angular,  somewhat  branching  stems,  which  often 
attain  a  length  of  15  feet.  The  leaves  are  lobed.  The 
flowers  are  pale  greenish-yellow.  The  fruit  varies  in  shape 
and  has  a  firm  fleshy  rind  and  a  tender  watery  pulp,  which 
is  usually  reddish  in  color  and  sometimes  purpHsh,  yellowish 
or  white.  The  skin  or  rind  varies  in  thickness  from  ^i  inch, 
in  such  varieties  as  White  Gem,  Gray  Monarch,  and  Hoosier 
King,  to  I  inch  in  the  Black  Spanish,  Nabob,  and  Golden 
Gate.  The  weight  of  the  fruit  frequently  reaches  23  or  25 
pounds. 

Geographical.— The  watermelon  is  indigenous  to  tropical  and  South  Africa. 
It  has  been  cultivated  for  centuries;  Egyptian  paintings  show  that  these 
peoples  cultivated  them. 

Types  and  Varieties. — The  varieties  of  Citrullus  vulgaris 
may  be  divided  into  two  general  types: 

1.  Common  Watermelon. — Flesh  of  fruit  comparatively 
tender  and  watery. 

2.  Citron. — Flesh  of  fruit  very  firm.  As  compared  with 
watermelons,  the  citron  feels  much  more  soHd.  The  citron 
is  used  for  making  sweet  pickles  and  preserves.  It  is  not 
eaten  in  the  raw  state.  The  juice  of  the  citron  is  added  in 
equal  parts  to  that  of  such  fruits  as  peaches,  cherries  and 
others  whose  juices  will  not  "jell"  by  themselves  to  make 
them  produce  jelly.  The  citron  has  a  large  amount  of 
pectin  in  the  cell  walls.  This  is  the  substance  in  fruits 
which  causes  their  juice  to  "jell." 


624  BOTAiSTY  OF  CROP  PLANTS 

The  citron  is  not  to  be  confused  with  the  true  citron  {Citrus 
medico)  (see  page  480) . 

Rane  divides  the  varieties  of  watermelons  into  six 
"classes:"  (i)  light  green  (Light  Icing,  Gray  Monarch); 
(2)  medium  green  (Fordhook  Early,  Jackson);  (3)  dark 
green  (Black  Spanish,  Mountain  Sweet,  Cannon  Ball) ;  (4) 
light-striped  (Golden  Gate,  Delaware,  Hoosier  King,  Rattle- 
snake, Santiago) ;  (5)  dull-striped  (Price  of  Georgia,  Orange, 
Triumph);  and  (6)  mottled  green  (Nabob  Phinney's  Early). 
These  "classes"  are  subdivided  into  "types"  according  to 
shape  of  fruit,  arid  the  "types"  are  each  divided  into  two 
groups:  those  with  light  seeds,  and  those  with  dark  (black 
or  brown)  seeds. 

References 

CoRBETT,  L.  C:  Cucumbers.     U.  S.  Dept.  Agr.  Farmers'  Bull.  254:  1-30, 

1906. 
Crocker,  W.,  Knight,  L.  S.,  and  Robert  E.:  The  Peg  of  the  Cucurbitaceae. 

Bot.  Gaz.,  50:  321-339,  1910. 
Griffin,  H.  H.:  The  Cantaloupe.     Colo.  Agr.  Exp.  Sta.  Bull.  62:  1-18,  1901. 
Pammel,  L.  H.:  Crossing  of  Cucurbits.     Bull.  Torrey  Bot.  Club,  20:  358-359. 

1893. 
Results  of  Crossing  Cucurbits.     la.  Agr.  Exp.  Sta.  Bull.  23:  906-917,  1894. 
Rane,  F.  W.:  Fertilization  of  the  Muskmelon.     Proc.  Soc.  Prom.  Agr.  Sci., 

150-151,  1898. 
IT.  Classification  of  Watermelons.     N.  H.  Agr.  Exp.  Sta.  Bull.  86:  95-107, 

1901. 


CHAPTER  XL 
COMPOSITE  (Thistle  FamUy) 

The  composite  or  thistle  family  is  one  of  the  largest  of  the 
plant  kingdom,  consisting  of  about  10,000  species  in  about 
760  genera;  it  has  a  wide  geographical  distribution. 

Representatives  of  the  family  are  considered  to  be  among 
the  most  complex  of  plants,  and  among  Dicots,  of  the  highest 
evolutionary  rank.  They  show  a  combination  of  characters 
which  place  them  high  in  the  scale  of  evolution.  These  are: 
union  of  petals  (sympetaly),  inferior  ovary  (epigyny),  seed- 
Hke  fruit,  pappus,  united  (syngenesious)  anthers,  head 
inflorescence,  diclinism,  and  dimorphism. 

Comparatively  few  species  of  this  large  family  are  of 
economic  value.  The  most  important  are  common  lettuce, 
Jerusalem  artichoke,  endive,  salsify,  and  dandelion.  The 
following  is  a  short  list  of  the  less  important  representatives 
of  the  family:  yarrow  {Achillea),  Chrysanthemum,  sage  and 
wormwood  {Artemisia  spp.),  sunflower  {Helianthus) ,  Arnica, 
Aster,  goldenrod  {Solidago),  sow-thistle  {Sonchus),  Dahlia, 
marigold  {Calendula),  rabbit-brush  {Chrysothamnus),  flea- 
bane  {Erigeron),  everlasting  (Antennaria),  Spanish  needles 
{Bidens),  and  thistle  {Carduus). 

Habit.— This  large  family  is  made  up  mostly  of  herbaceous 
forms;  there  are  a  number  of  shrubs,  however,  and  a  few 
tropical  tree  species.  Many  of  them,  as  the  dandelion  and 
lettuce,  have  a  milky  juice,  while  in  others  the  sap  is  watery, 
resinous,  acrid  or  bitter. 

Leaves. — The  leaves  are  either  alternate  or  opposite, 
rarely  in  whorls  (verticillate) ,  and  usually  without  stipules. 
40  625 


626 


BOTANY  OF  CROP  PLANTS 


Inflorescence.— The  inflorescence  (Fig.  254,  A)  is  a  head, 
the  flowers,  usually  numerous,  being  mounted  on  a  common 
receptacle  which  is  subtended  by  an  involucre.  A  "sun- 
flower" is  not  a  single  flower  in  the  botanical  sense,  but  a 
group  or  composite  of  individual  flowers.     The  receptacle 


Fig.  254. — Jerusalem  artichoke  (Helianthus  tuberosus).  A,  lengthwise 
section  of  head,  X  i;  -B,  ray  flower,  X  6;  C,  disk  flower,  cut  lengthwise,  X  6. 
{A  after  Baillon.) 

varies  in  shape  from  flat  to  convex  or  conical.  The  recep- 
tacle is  naked  or  there  are  chaffy  scales  subtending  the  flower; 
its  surface  is  smooth,  pitted,  or  honeycombed.  The  involu- 
cral  bracts  also  vary  widely  in  shape,  from  narrow  and  spine- 
like to  broad  and  leaf-like;  they  occur  in  one  or  more  series. 


COMPOSITE 


627 


Flowers.— The  flowers  may  be  perfect,  polygamous, 
monoecious  or  dioecious.  There  are  two  sorts  of  flowers  in 
the  composite  family:  (i)  Disk  or  tubular,  and  (2)  ray  or 
ligulate. 

Disk  Flowers  (Fig.  254,  C).— These  are  perfect  and  regular 
and  make  up  the  so-called  disk  of  the  composite  "flower." 
For  example,  the  disk  of  the  "sunflo.wer"  is  the  center.  The 
calyx  is  modified,  taking  the  form  of  a  few  or  large  number  of 
bristles,  awns,  scales  or  teeth;  this  modified  calyx  is  termed 
a  pappus.  In  some  mstances,  the  pappus  is  entirely  wanting. 
It  is  attached  to  the  apex  of  the  inferior  ovary.  The  corolla 
is  tubular  and  five-lobed.  The  five  stamens  are  attached 
to  the  corolla  and  alternate  with  its  lobes;  the  anthers  are 
united  into  a  tube.  In  one  genus  (Kuhnia),  the  anthers  are 
distinct  or  nearly  so.  The  anthers  are  often  appendaged  at 
the  apex  and  sometimes  caudate  or  sagittate  at  the  base; 
pollen  grains  are  spherical,  often  rough  or  prickly.  There 
is  a  single  pistil,  an  inferior  one-celled  and  one-seeded  ovary, 
and  a  single  style  which  is  entire  (in  sterile  flowers)  or  two- 
cleft  at  the  apex;  the  style  branches  are  often  tipped  with 
appendages. 

Ray  or  Ligulate  Flowers  (Fig.  254,  B).— These  are  usually 
imperfect  and  irregular.  They  have  a  pappus  and  a  strap- 
shaped  corolla  with  either  a  long  or  short  tube. 

The  composite  family  is  divided  into  two  large  groups,  the 
Liguliflorce  and  TuhuliflorcB.  The  dandelion,  chicory,  and 
lettuce  are  representatives  of  the  former,  and  sunflower, 
Jerusalem  artichoke,  daisy,  fleabane,  aster,  and  goldenrod 
typical  members  of  the  latter  group.  In  the  Liguliflorce, 
ligulate  or  strap-shaped  flowers  are  the  only  sort  present;  in 
these,  the  flowers  are  perfect  and  consist  of  five  stamens  with 
their  anthers  united  into  a  tube,  a  one-celled,  one-seeded 
ovary,  a  single  style,  and  a  two-lobed  stigma;  the  pappus  may 


628  BOTANY  OF  CROP  PLANTS 

be  present  or  wanting.  In  the  TuhuliflorcB,  there  are  both 
disk  and  ligulate  flowers,  the  former  occupying  the  center 
of  the  head,  while  the  ligulate  ones  are  at  the  margin  of  the 
receptacle,  and  are  called  ray  flowers.  In  the  Tuhiliflorce,  the 
ray  or  ligulate  flowers  are  very  frequently  pistillate.  In 
both  types  of  flowers,  the  fruit  (achene)  is  one-seeded  and 
indehiscent.  The  pappus  is  usually  persistent  at  the  apex 
of  the  fruit,  serving  as  a  means  of  dissemination  by  the 
wind. 


Key  to  Important  Genera 

Flowers  with  ligulate  corollas  only;  flowers  perfect. 
Pappus  of  plumose  bristles,  Tragopogon  (salsify). 
Pappus  not  plumose. 

Pappus   of   mere   chaffs  or  these  reduced  and  united  into  a  crown, 

dehor ium  (chicory). 
Pappus  of  capillary  bristles. 

Achenes  flattened,  Lactuca  (lettuce). 
Achenes  not  flattened,  Taraxacum  (dandelion). 
Flowers  with  tubular  corollas  or  none,  or  only  the  ray  flowers  with  ligulate 
corollas. 
Anthers  long- tailed  at  the  base  and  with  long  appendages  at  the  tip;  heads 

large;  rays  none,  Carduus  (thistle). 
Anthers  not  tailed  at  the  base;  flowers  tubular  only,  or  tubular  and  ligulate. 
Receptacle  naked. 

Ray  flowers  yellow;  involucral  bracts  scarcely  imbricated,  Arnica. 
Ray  flowers  never  yellow;  involucral  bracts  well  imbricated. 
Bracts  of  involucre  imlaricated  in  several  series.  Aster. 
Bracts  of  involucre  in  but  one  or  two  series,  Erigeron  (fleabane). 
Receptacle  chaffy. 

Bracts  of  involucre  foliaceous,  Helianthus  (Jerusalem  artichoke  and 

sunflower). 
Bracts  of  involucre  dry,  thin,  and  papery. 
.  Receptacle  chaffy,  Achillea  (yarrow). 
Receptacle  not  chaffy,  naked,  or  sometimes  hairy. 
Ray  flowers  present.  Chrysanthemum. 
Ray  flowers  none,  Artemisia  (sage  and  wormwood). 


COMPOSIT.E 


629 


LACTUCA  SATIVA  (Garden  Lettuce ) 

Description. Coniiiion  garden  IclUue  is  a  tall,  annual 
leafy  liefh,  with  a  niilk\-  juice.  There  is  llirown  up  from 
a  short  stem  early  in  the  season  a  cluster  of  leaves  varying 
consideralDly  in  shape,  character,  and  color,  in  the  different 
varieties.  Later  in  the  season,  a  "seed  stalk"  is  sent  up. 
Tracy  found  that,  at  Washington,  I).  C,  the  first  appearance 


Fig.   255. — Asparagus  lettuce,  var.  angustana.      {Aficr  CorbcU.) 

of  the  seed  stalk  after  sowing  seed,  varied  from  59  (in 
Emperor  Forcing)  to  H2  (in  Italian  Ice)  days.  The  leaves 
are  alternate,  denticulate  or  pinnatifid,  sessile  or  auriculate- 
clasping,  sometimes  spinulose-margined,  the  lowest  ones 
larc^e,  and  the  upper  much  smaller.  The  inflorescence  is  a 
panicle.  The  flowers  are  yellowish  or  )-ellowish-white,  the 
involucre  cylindric,  the  bracts  of  which  are  imbricated  in 
several  series,  the  outer  shorter.  'Hie  receptacle  is  tlat  and 
naked.     The  corolla  rays  are  truncate  and  tive-toothed  at 


6^0 


BOTANY    OF   CROP   PLANTS 


llu-  end.  'I'lu'  anllicrs  are  sa.G;itlatc  at  the  base.  The  style 
branches  are  slender.  1'he  (ichriics  are  oxal.  oblont:;,  or 
Hnear,  tlat.  three  to  ti\e-ribbed  on  each  l;ui\  narrowed  above 
or  contracted  into  a  narrow  beak  which  bears  a  hiru;e  number 


Fic.  256.- r 


\fh-r  Corln-ll.) 


of  soft,  capiUary,  white  or  brown  pap[)us  bristles.  The 
achenes  \ary  in  color:  whitish,  blackish,  yellowish,  or 
brownish. 

Origin,  and  Geographical.  It  is  quite  generall\  conteded 
by  botanists  that  our  garden  lettuce  (L.  saliva)  is  originated 
from  the  wild  species,  L.  scariola.     This  latter  species  grows 


COMPOS  IT. F- 


631 


wild  in  Europe.  Canary  Isles,  Madeira,  Algeria,  Abyssinia, 
and  Eastern  Asia,  and  has  also  become  naturalized  in  the 


Fk;.    2.S7.  ^-Cos  lettuce,  var.  romana.      (Aflrr  Corhcll.) 

liiiled  States,  where  it  is  often  a  troublesome  weed.      In 
this  eountrv,  L.  scariola  is  distributed  from  New  York  to 


Fig.    .'sS.-Hcad  Ictlucc,  var.  capitata.      {After  Corlnil.) 

Minnesota  and  Missouri.  The  close  relation.ship  between 
/..  saliva  and/.,  scariola  is  shown  by  the  fact  that  they  readily 
cross. 


032  BOTANY  OF  CROP  PLANTS 

There  are  a  number  of  native  species  of  Lactuca  in  this 
country.  Britton  and  lirown  mention  eight  species  native 
of  the  eastern  and  northern  United  States,  besides  the  intro- 
duced L.  scariola.  This  hitter  species  is  commonly  known 
as  the  "compass  plant." 


' 

Sp 

Fu;.  259. — Salsify  (Tragopogon  porrifolius).  From  left  to  right:  unopcr. 
flower  head;  side  view  and  face  view  of  open  flower  head;  achene  with  pappus  at 
tip  of  beak. 

Types  of  Lettuce.     Four  types  or  botanical  varieties  of 
cultivated     lettuce     are     recognized.      These     nui}'     be     tlis- 
tinguished  by  the  following  artificial  key: 
Kl:y  to  Tyl>i:s  of  Li:TTi;cii 
Basal  IcaN'cs  narrow,  distinctly  lanceolate,  L.  saliva  \ar.  anguslana  (asparagus 

lettuce). 


COMPOSITvE 


633 


Basal  k-avcs  l)n)a(l,  spal 
Leaves  deeplv  ml   01 


ulalo,  oval  t.)  roun-lish,  always  rounded  at  the  tip. 
1   ..11  liie  cd^rs,  L.  idtiv'i  var.  itilyhacca  (culling  or  cut - 
leaved  lelUm). 
Leaves  entire  or  but  slightly  toothed.  ,       •  ,    ,       ,    > 

Leaves  forming  a  rather  compacl  roundish  or  llalt.sh  head;  leaves  ncvu 
d  c  cle  Iv  SI  IT  and  Hat,  L.  saii.a  var.  capU.ia  (hea.l  or  cabbage  ellucc) 
Leavel  forming  a  conical  or  cylin.lrical-shaped  head;  leaves  slra.ght  and 
slilT   L.  Siit'mi  var.  romana  (,cos  lelluce). 


Fi(..   260. 


pappus 


-SinKlc  llowcr  of  salsify  (Tragopogon  p..rrif.jUus).  X  -M.. 


'I'racy  classifies  the  American  varieties  of  lettuce  as  tol- 
lows:  (r)   butter  varieties,   (2)   crisp  varieties,  and   (.^)   os 
varieties.     These  three  groups  are  further  subdivided. 
TRAGOPOGON  PORRIFOLIUS  (Salsify  or  "Oyster  Plant") 

Description.-Salsify  is  a  hardy  perennial  plant  hnu^  a 
tleshy  r.).)t.  The  rools  are  about  12  inches  Ion-  wilh  a 
(liam'eler  of  about  2  inches  at  the  top;  the  skin  is  grayish 
white  The  sloLs  are  usually  somewhat  branched  and  succu- 
lent Wiien  grown  from  seed,  a  seed  stalk  is  sent  up  the 
second  season  to  a  height  of  2  to  4  feet.  The  lonrs  are  alter- 
nate, entire,  Hnear-lanceolate,  clasping  at  the  base,  and  glau- 
cous. Heads  (Fig.  259)  are  single  at  the  end  of  rather  long 
thickened    peduncles,    which   are   often   holhnv    for   several 


634  BOTANY  OF  CROP  PLANTS 

inrhcs  below  the  head.  The  heads  are  purple  and  open 
earl}'  in  the  iiiorninjj;  but  usually  close  by  noon.  The  in- 
volucrc  is  cylindrical,  the  bracts  nearly  ecjual.  in  one  series, 
linear-lanceolate,  and  usually  much  longer  than  the  rays 
of  the  llovvers.     The  corollas  (Fig.  260)  are  truncate  and  tive- 


Fiij.   261. — Salsify  (Tragopogun  purrifolius).      Hcadiu  fruit;  receptacle 
after  having  shed  the  achenes;  single  achene. 

toothed  at  the  apex.  The  anthers  are  sagittate  at  the  base. 
The  style  branches  are  slender.  Achcncs  are  linear,  and  termi- 
nated by  slender  beaks,  the  outer  ones  being  covered  with 
tubercles,  particularly  on  the  ribs  below.  The  pappus  is 
grown  together  at  the  base,  is  plumose,  and  has  interwebbed 
branches  (Fig.  261). 


COMPOSITE  635 

Geographical,  and  Closely  Related  Species.— The  species 
is  a  native  of  southern  Europe.  It  is  quite  widely  distributed 
in  this  country  in  fields  and  waste  places,  probably  as  an 
escape  from  cultivation.  A  yellow-flowered  salsify  (r. 
pratensis),  naturalized  from  Europe,  is  also  quite  widely 
distributed  here.  The  Spanish  salsify  or  Spanish  oyster 
plant  {Scolymus  hispanicus),  has  a  root  much  like  that  of 
common  salsify,  but  the  plant  differs  from  common  salsify 
in  the  following  respects:  the  roots  are  of  a  lighter  color  and 
longer,  the  leaves  prickly,  and  the  flowers  yellowish.  The 
black  salsify  {Scorzonera  hispanica),  also  a  m_ember  of  the 
Composite  family,  bears  a  black,  fleshy,  edible  tap  root. 
It  differs  from  common  salsify  in  that  its  leaves  are  broader, 
flowers  yellow,  and  its  involucral  bracts  are  in  many  series. 

Uses.— Salsify  is  grown  for  its  fleshy  roots  which  have 
somewhat  the  flavor  of  oysters,  hence  the  common  name, 
"oyster  plant."  They  are  used  both  as  a  cooked  vegetable 
and  as  a  relish. 

CICHORIUM  (Chicory  or  Succory,  and  Endive) 

Description.— All  the  species  of  this  genus  are  branching 
herbs.  The  leaves  are  alternate,  mostly  basal,  the  cauHne 
ones  small  and  bract-like.  The  heads  are  large,  and 
peduncled  or  in  sessile  clusters  along  the  branches.  The 
bracts  of  the  involucre  are  in  two  series,  the  outer  spreading, 
the  inner  erect.  The  receptacle  is  flat,  naked,  or  fringed  with 
small  hairs.  The  corolla  rays  are-  truncate  and  five-toothed 
at  the  apex.  The  achenes  are  five-angled  or  five-ribbed, 
truncate,  and  not  beaked.  The  pappus  consists  of  a  number 
of  short  scales. 

Geographical. — The  species  of  Cichorium  are  natives  of  the  Old  World. 
There  are  two  of  economic  importance:  Cichorium  intybus  (chicory)  and 
Cichorium  endiva  (endive).  .     ■ 


636  BOTANY   OF  CROP  PLANTS 

CICHORIUM  INTYBUS  (Chicory  or  Succory) 

Description  (Fig.  262). — This  is  a  perennial  species  from  a 
long,  deep  tap  root,  which  sends  up  a  stiff,  rough-hairy, 
branched  stem  to  a  height  of  i  to  3  feet.  Radical  leaves  are 
numerous,  and  spreading  on  the  ground;  the  upper  leaves 
are  smaller,  lanceolate  or  oblong,  lobed  or  entire,  clasping 
and  auricled  at  the  base.  The  heads  are  axillary.  The 
flowers  are  blue  or  purplish,  and  sometimes  white. 

The  species  is  a  native  of  Europe.  It  is  introduced  into 
the  United  States,  occurring  as  a  ruderal  from  Nova  Scotia 
to  North  Carolina,  and  west  to  Minnesota  and  Missouri. 

Uses,  and  Varieties. — The  roasted  root  of  chicory  has  been 
used  as  a  substitute  for,  and  an  adulterant  of,  coffee.  The 
young  roots  are  sometimes  boiled,  and  the  leaves  used  as 
"greens"  or  served  fresh  as  a  salad.  The  plant  is  some- 
times forced  in  the  winter  to  produce  a  cluster  of  loose 
leaves  for  use  in  salads.  Such  clusters  of  leaves  are  called 
"Barbe  de  Capuchin."  Common  varieties  of  chicory  are: 
Common,  Large-rooted  Madgebury,  Long-rooted  Brunswick 
and  Improved  very  Large-leaved.  Witloof  chicory  is  an 
improved  variety  of  Belgian  origin. 

CICHORIUM  ENDIVA  (Endive) 

Description. — Endive  is  an  annual  or  biennial  herb  with 
numerous  basal  leaves  which  vary  much  in  character;  they 
may  be  merely  toothed,  the  teeth  large  or  small  and  numerous, 
or  pinnatifid;  some  of  the  most  desirable  varieties  have  the 
leaf  margins  very  much  curled.  The  upper  leaves  are  smaller, 
and  auricled  at  the  base.  The  stem  often  rises  to  a  height 
of  3  feet;  it  is  hollow,  terete,  branched,  and  smooth  or 
slightly  hirsute.  The  flowers  are  purple  and  sometimes  white. 
The  achenes  are  angular  and  ribbed. 


COMPOSITiE 


637 


Fig.  262. — Chicory  (Chicorium  intybus).  A,  sessile  clusters  of  flowers  in 
axils  of  bracts,  Xi;  B,  single  floral  bract  enlarged,  X  4;  C,  open  flower,  face 
view,  enlarged;  D,  basal  leaf,    X  i>^. 


638 


BOTANY  OF   CROP  PLANTS 


Geographical  Distribution,  and  Economic  Uses. — Endive 
is  a  native  of  India.  It  is  cultivated  to  a  great  extent  in 
the  gardens  of  European  countries  and  to  some  extent  in 


Fig.  263. — Tubers  of  Jerusalem  artichoke  (Helianthus  tuberosum).     {After 
Vilmorin.) 


the  United  States.  The  best-known  variety  grown  here  is 
the  Green  Curled.  The  plant  is  cultivated  for  the  young 
basal  leaves  which  are  blanched  and  used  as  a  salad. 


COMPOSITE  639 

HELIANTHUS  TUBEROSUS  (Jerusalem  Artichoke) 
Description.— The  Jerusalem  artichoke  is  a  perennial  herb 
arising  from  thick,  fleshy  rootstocks  that  bear  oblong  tubers 
(Fig.  263).  The  above-ground  stems  attain  a  height  of  6  to  12 
feet;  they  are  stout,  branching,  terete  and  hirsute.  The  leaves 
are  alternate  above,  opposite  below,  simple,  ovate  or  ovate- 
oblong,  firm,  three-nerved  at  the  base,  narrowed,  rounded, 
truncate  or  slightly  heart-shaped  at  the  base,  acuminate  at 
the  apex,  and  long  petioled.  The  heads  are  solitary  or  in 
corymbs.  Tubular  (disk)  and  hgulate  (ray)  flowers  are  both 
present;  the  rays  are  yellow  and  the  disk  is  also  yellow  (Fig. 
254).  The  involucre  is  hemispheric,  with  lanceolate,  acumi- 
nate hirsute  or  cihate,  squarrose  bracts.  There  are  12  to  20 
rays.  The  receptacle  is  chaffy;  the  chaff  subtends  the  disk 
flowers.  The  achenes  are  thick,  somewhat  four-angled,  and 
pubescent.     The  pappus  consists  of  two  deciduous  scales. 

Geographical. — The  Jerusalem  artichoke  (also  called  Earth  Apple,  Canada 
Potato,  Girasole  and  Topinambour)  is  native  to  this  country  and  is  found 
from  New  Brunswick  and  Ontario  to  Georgia  and  Arkansas,  west  and  north 
to  Canada.     It  is  grown  as  a  crop  more  in  Europe  than  in  America. 

Closely  Related  Species. — The  Jerusalem  artichoke  is 
closely  related  to  the  "globe  artichoke"  {Cynara  scolymus) 
which  in  fact  belongs  to  the  same  family.  Composite. 
Cynara  scolymus  is  sometimes  cultivated  for  the  flower  heads 
and  leaves.  The  thick  receptacle  together  with  the  fleshy 
bases  of  the  scales  of  the  involucre  is  used  as  a  vegetable. 
The  plant  may  be  distinguished  further  from  Jerusalem 
artichoke  by  its  blue  or  violet-purple  flowers,  and  its  large, 
wooly,  pinnatifid  leaves. 

Uses. — The  tubers  of  Jerusalem  artichoke  are  used  both 
as  a  vegetable  and  as  a  food  for  stock.  Hogs  are  turned  into 
the  field  and  permitted  to  root  the  tubers  from  the  ground. 

References 
Tracy,  W.  W.:  American  Varieties  of  Lettuce.     U.  S.  Dept.  Agr.  Bur.  Plant 
Ind.  Bull.  69:  1-103,  1905. 


GLOSSARY 

Abaxile. — Situated  off  the  axis. 

Abortive. — Imperfectly  formed  or  rudimentary. 

Acaulescenl. — Without  an  obvious  stem. 

Accumbent  (cotyledons). — Their  edges  against  the  hypocotyl. 

Achene  (akene). — A  one-celled,  dry,  indehiscent  fruit  in  which  the  testa 
and  pericarp  are  not  firmly  attached. 

Aero  petal. — Developing  from  the  outside  (below)  toward  the  inside  (above). 

Actinomorphie. — Regular,  ray-shaped;  said  of  a  flower  when  it  can  be 
divided  into  symmetrical  halves  by  radial  planes. 

Aeuminaie. — Taper-pointed. 

Acute. — Merely  sharp-pointed,  or  ending  in  a  point  less  than  a  right  angle. 

Adnate. — Grown  fast  to;  applied  to  the  growing  together  of  unlike  parts. 

Adventitious. — Out  of  the  ordinary  place,  as  applied  to  buds  or  roots. 

Aestivation. — The  arrangement  of  parts  in  the  bud. 

Alliaceous. — With  odor  and  taste  of  onions  and  garlic. 

Alternate  (buds,  flower  parts,  leaves,  etc.).  One  after  another  singly  at 
the  nodes. 

Ament. — Scaly  unisexual  spike  of  flowers. 

Amphitrcpous  (ovules).  Half-inverted  and  straight,  with  the  hilum  about 
the  middle,  and  micropyle  terminal. 

Anatropous  (ovules). — Inverted,  straight  and  with  micropyle  next  the 
hilum. 

Androecitim. — The  stamens  collectively. 

Annual  (plant). — Produces  flowers,  fruit,  and  seed  the  same  year  it  is 
raised  from  seed,  and  then  dies.  Winter  annuals  germinate  in  autumn,  and 
produce  seed  the  following  spring  or  summer. 

Annular. — Forming  a  ring  or  circle,  as  embryo  of  beet. 

Apetalous. — Without  petals,  as  in  buckwheat,  etc. 

Apical. — At  the  tip  or  apex. 

Apocarpy. — Condition  in  which  the  carpels  are  separate. 

Apopetaly. — Condition  in  which  petals  are  separate  and  distinct. 

Articulated. — Jointed. 

Auricle. — Ear-like  structure. 

Auriculate. — Eared;  furnished  with  ear-like  appendages. 

Autogamy. — Pollination  in  which  pollen  is  transferred  from  the  anthers  to 
the  stigma  of  the  same  flower. 

Awn. — Bristle-like  structure,  or  beard. 

41  641 


642  BOTANY  OF  CROP  PLANTS 

Awned. — Furnished  with  an  awn  cir  beard. 
Axillary  (buds,  etc.)- — In  the  axil. 

Basal. — Belonging  to  or  attached  to  the  base. 

Berry. — A  fleshy  fruit,  with  mesocarp  and  endocarp  fleshy  throughout, 
and  seeds  imbedded  therein,  as  grape,  currant,  etc. 

Biennial. — Of  two  years'  duration;  the  first  year  from  seed,  the  second  year 
flowering  and  fruiting,  then  dying;  as  in  sugar  beet,  carrot,  etc. 

Bipinnate  (leaf). — Twice  pinnate. 

Blade. — Expanded  portion  of  a  leaf. 

Bloom. — The  whitish,  powdery,  and  waxy  secretion  of  epidermal  cells. 

Bract. — A  reduced  scale-like  leaf,  above  the  regular  foliage  leaves. 

Bracteclale. — Bearing  bractlets. 

Bractecle. — A  small  bract. 

Bulbils. — Small  bulbs  borne  underground,  as  in  garlic. 

Bulblets. — Small  bulbs  borne  above  ground,  as  in  tree  onions. 

Cambium. — The  growing  layer  in  the  vascular  bundle. 

Campanulate. — Bell-shaped. 

Campylotropous  (ovule  or  seed). — Curved  so  as  to  bring  the  apex  and  base 
near  together. 

Capillary. — Hair-like  in  form. 

Capitate. — Knob-like;  shaped  like  a  head. 

Caprification. — The  artificial  process  of  pollinating  figs. 

Capsule  (pod). — A  dry,  dehiscent  fruit  of  two  or  more  carpels. 

Carina. — Keel. 

Carpophore. — A  slender  stalk  to  which  the  mericarps  of  the  umbelliferous 
fruit  are  attached. 

Caryopsis. — Synonym  of  grain — a  dry,  indehiscent  one-seeded  fruit  in 
which  the  pericarp  and  testa  closely  adhere. 

Catkin. — Ament.     Scaly  spike  of  flowers. 

Caudate. — •Tailed;  with  a  slender  tail-like  appendage. 

Caulijlcrus. — Stem-flowering;  trunks  bearing  flowers,  as  in  figs. 

Cauline. — Pertaining  or  belonging  to  the  stem. 

Chasmogamy. — Flowers  that  regularly  open  are  said  to  show  chasmogamy. 

Ciliate. — Fringed  with  marginal  hairs. 

Cladophyll. — A  leaf-like  branch. 

Claw. — The  narrow  or  stalk-like  base  of  some  petals. 

Cleft. — Cut  about  halfway  to  midrib  or  median  line. 

Coleoptile. — ^Leaf  sheath  in  grasses. 

Colecrhiza. — A  sheath  about  the  root. 

Commissure. — The  contiguous  surfaces  of  two  carpels,  as  in  the  fruit  of 
Umbelliferas. 


GLOSSARY  643 

Conduplicate. — Folded  lengthwise. 

Connivent. — Overlapping  or  brought  close  together. 

Convergent. — Margins  touching. 

Convolute. — Rolled  lengthwise. 

Cordate. — Heart-shaped. 

Corneus. — Horny. 

Corm. — The  swollen,  fleshy,  and  solid  base  of  a  stem. 

Cortex. — Bark  region,  from  epidermis  to  endodermis. 

Corymb. — An  indeterminate  type  of  inflorescence  that  is  flat-topped. 

Corymbose. — Corymb-like. 

Crenate. — Margins  with  rounded  teeth. 

Crenulate. — With  very  small  rounded  teeth;  diminutive  of  crenate. 

Culm. — The  hollow  stem  of  grasses  and  sedges. 

Ctilicle. — A  thin  covering  of  a  waxy  substance  called  cutin  on  the  outer 
wall  of  epidermal  cells. 

Cyme. — A  determinate  type  of  inflorescence,  in  which  the  first  flowers  to 
open  are  those  toward  the  inside. 

Cymose. — Cyme-like,  or  bearing  cymes. 

Decompound. — Several  times  compound  or  divided,  as  in  leaves  of  carrot 

Decumbent. — More  or  less  prostrate,  but  with  the  tips  ascending. 

Decurrent  (leaf). — Extending  down  the  stem  below  the  point  of  insertion. 

Dehiscence. — The  opening  of  a  fruit  or  anther. 

Dehiscent. — Splitting  open. 

Dentate. — Sharp-toothed;  teeth  directed  forward. 

Denticidate.— Diminutive  of  dentate;  furnished  with  very  small  sharp  teeth. 

Diadelphous  (stamens). — United  into  two  sets,  as  in  many  legumes. 

Diaphragm. — A  dividing  partition. 

Dichogamy. — A  condition  in  which  stamens  and  pistils  do  not  mature 
simultaneously. 

Diclinism. — Stamens  and  pistils  in  separate  flowers,  as  in  dioecious  and 
monoecious  plants. 

Digitate. — The  spreading  of  segments  like  the  fingers  from  palm  of  hand. 

Dilated . — Expanded . 

Dimorphism. — The  occurrence  of  two  distinct  forms,  as  in  flowers  of  buck- 
wheat. 

Dioecious. — Bearing  staminate  and  pistillate  flowers  on  different  individual 
plants. 

Dissected. — Divided  into  many  lobes  or  segments. 

Distichous. — Two-ranked,  as  the  leaves  of  grasses. 

Divergent. — Spreading  apart. 

Divided. — Segmented  to  the  midline,  midvein,  or  base. 

Dorsal. — On  the  back;  surface  of  member  turned  away  from  the  main  axis. 


644  BOTANY  OF  CROP  PLANTS 

Drupe. — A  one-seeded,  fleshy  fruit  in  which  the  endocarp  is  stony,  the 
mesocarp  fleshy,  and  exocarp  skin-like. 
Drupelet. — A  small  drupe,  as  in  raspberry. 

Elliptic. — Oval,  or  the  shape  of  an  ellipse. 

Emarginate. — Notched  at  the  apex. 

Embryo. — Young  plant  within  the  seed. 

Endocarp. — Inner  wall  of  pericarp  (ovary  wall). 

Endosperm. — The  stored  food  supply  in  a  seed. 

Entire. — Without  divisions,  lobes,  or  teeth;  usually  refers  to  margins  of 
leaves,  petals,  and  sepals. 

Epicalyx. — Extra  bract-like  segments  below  the  calyx  in  the  strawberry. 

Epigynous. — Ovary  inferior;  flower  parts  above  the  ovary  or  apparently 
growing  from  its  tip. 

Epiphyllous. — Borne  on  leaf  surface. 

Epiphyte. — Growing  upon  another  plant,  but  gaining  from  it  no  nutriment. 

Episperm. — Testa;  seed  coats.    . 

Erose. — With  an  irregular  margin,  as  if  chewed. 

Etiolate. — To  whiten,  or  blanch,  by  the  exclusion  of  light. 

Exocarp. — Outer  wall  of  pericarp  (ovary  wall). 

Exserted  (stamens). — Extending  beyond  the  other  flower  parts. 

Exstipulate. — Without  stipules. 

Extravaginal. — Referring  to  branches  in  grasses  which  force  their  way  out 
through  the  base  of  the  leaf  sheath. 

Extrorse. — Turned  outwards;  usually  referring  to  anthers  which  shed  their 
pollen  towards  the  outside  of  the  flower. 

Falcate. — Shaped  like  a  scythe. 

Fascicle. — Bundle  or  cluster. 

Fertile. — Capable  of  bearing  fruit  or  seed;  apphed  to  flowers  with  pistils 
or  to  anther  with  pollen. 

Fertilization. — A  sexual  process  in  which  two  dissimilar  gametes  fuse. 

Fibrous. — Fiber-like,  usually  referring  to  root  system  of  many  small  thread- 
like roots. 

Filament. — Thread;  stalk  of  stamen. 

Filamentous. — Thread-like. 

Fimbriated. — Fringed. 

Foliaceous. — Leaf-hke  in  form  and  texture. 

Follicle. — A  dry,  dehiscent  fruit  with  one  carpel  which  splits  along  the 
ventral  suture. 

Funnelform. — Funnel-shaped. 

Geitonogamy. — A  method  of  pollination  in  which  pollen  is  taken  from  anther 
to  stigma  of  another  flower  on  same  plant. 


GLOSSARY 


64s 


Geniculate— Bent  abruptly  at  an  angle,  like  the  bent  knee. 
Glabrotis.— Smooth;  without  hairs,  scales,  or  bristles. 
Glandtdar. — Furnished  with  glands. 

Glaucous—Covered  with  a  fine,  waxy-like  covering  (bloom)  which  rubs 
off  easily. 
Globose. — Globe-shaped. 
Glob^llar. — Globe-shaped. 

G/Mwe.— General  name  for  floral  bract  of  grasses  and  sedges. 
Gyncecium. — The  carpels  taken  collectively. 

fl"a<r/o<e.— Halberd-shaped;  basal  lobes  diverging. 

Head— An  indeterminate  type  of  inflorescence  in  which  the  flowers  are  in 
a  dense  cluster,  as  in  Composite. 

Hermaphrodite  (flowers).— Perfect,  both  stamens  and  pistils  present. 

Hyaline. — Thin  and  very  nearly  transparent. 

Hypocotyl.—Tha.t  portion  of  the  embryo  stem  below  the  cotyledons. 

Hypogean  (cotyledons).— Remaining  underground,  as  in  the  pea. 

Hypogynojis.~Ova.Ty  superior;  flower  parts  attached  below  the  ovary. 

Hilum.— The  scar  on  a  seed,  marking  the  attachment  of  a  seed  to  its  stalk. 

Hirsute.— CoveTed  with  stiff  hairs. 

Homogamy.— The  anthers  and  stigmas  mature  at  the  same  time. 

Imbricated. — Overlapping. 

Incised. — Cut  rather  deeply  into  sharp  lobes. 

Included  (stamens).— Not  extending  beyond  the  surrounding  parts. 

Incumbent  (cotyledons).— With  the  backs  against  the  hypocotyl. 

Indehiscent. — Not  splitting  open. 

Indigenous. — Native  to  the  region  of  growth. 

Inferior  (ovary). — Below  the  other  flower  parts. 

Inflexed. — Bent  inwards. 

Inflorescence. — A  flower  cluster. 

Integument. — Skin;  coat  or  protecting  layer. 

Internode. — The  interval  between  two  adjacent  nodes. 

Intravaginal.—'Keiexnng  to  branches  in  grasses  which  grow  out  between 
the  leaf  sheath  and  the  culm  (stem). 

/w/^-or^e.— Turned  inwards;  usually  referring  to  anthers  which  shed  their 
pollen  towards  the  inside  of  the  flower. 

Involucel. — A  secondary  involucre. 

Involucellate. — Furnished  with  involucels. 

Involucrate. — Furnished  with  an  involucre. 

Involucre.— A  series  of  bracts  that  subtend  an  inflorescence,  as  in  Compos- 
itae,  cotton,  etc. 

Irregular  (flower).— One  or  more  of  the  parts  of  a  series  are  dissimilar. 


646  BOTANY  or  CROP  PLANTS 


Keel. — Ridge,  like  the  keel  of  a  boat. 

Laciniate. — Cut  into  narrow,  rather  deep  segments. 

Lamella. — Plate. 

Lanceolate. — Lance-shaped. 

Lemma. — The  bract  (glume)  at  the  base  of  the  flower  in  grasses. 

Lenticular. — Shaped  like  a  double-convex  lens. 

Lignified. — Woody;  cell  walls  impregnated  with  lignin. 

Ligulate. — Strap-shaped. 

Ligule. — Appendage  at  juncture  of  sheath  and  blade  in  grasses,  or,  strap- 
shaped  corolla  in  Compositae. 

Linear. — ^Long  and  narrow,  its  sides  nearly  parallel. 

Lobed. — Divided  to  about  the  middle. 

Locule. — Cell  cavity. 

Loculicidal. — Refers  to  capsules  which  split  lengthwise  through  the  middle 
of  each  cell. 

Lodicules. — Small  scales  (inner  perianth)  surrounding  the  ovary  in  grasses. 

Lumen. — Cell  cavity. 

Lyrate. — ^Lyre-shaped;  the  end  lobe  of  pinnatifid  leaf  is  much  larger  than 
the  rest. 


Marginal. — Along  the  edge  or  margin. 
Median. — Middle. 
Medulla. — Pith. 

Mericarp. — One-half  of  the  fruit  of  Umbelliferae. 
Mesocarp. — Middle  layer  of  pericarp  (ovary  wall). 
Mesocotyl. — Axis  between  base  of  coleoptile  and  grain,  in  grasses. 
Micr'opyle. — The  opening  between  the  ovule  or  seed  coats. 
Microsporangium. — Anther  sac;  case  bearing  microspores. 
Monxcious. — Staminate   and   pistillate  flowers  in  different  inflorescences 
on  same  plant. 
Mucronate. — With  a  sharp  and  abrupt  point. 

Nerve. — Veins  or  ribs  in  bracts,  scales,  petals,  sepals,  etc. 
Node. — The  point  on  the  stem  from  which   a  leaf  or  leaves  arise;  the 
junction  of  two  internodes. 
Nucellus  (megasporangium). — -The  ovule  tissue  within  the  integuments. 
Nutlet. — A  small  nut. 

Oh. — A  prefix  signifying  inversion. 

Obcordate. — Heart-shaped,  with  broad  end  at  the  tij). 


GLOSSARY  647 

Oblate. — Flattened  at  the  ends. 

Obovate. — Egg-shaped  in  outline,  with  the  broader  end  at  the  tip. 

Obsolete. — Rudimentary,  or  entirely  absent. 

Obtuse. — Blunt  or  rounded  at  the  apex. 
•   Ocrece. — Sheathing  stipules  in  Polygonaceae. 

Orbicular. — Approximately  circular  in  outline. 

Orthotropous  (ovule). — Straight;  hilum  at  one  end  and  micropyle  at  the 
other. 

Ovate. — Egg-shaped  in  outline;  broader  end  at  the  base. 

Ovoid . — Egg-shaped . 

Ovule. — The  body  which  becomes  the  seed  after  fertilization. 

Palet  (palea). — Outer  perianth  segment  of  grass  flower. 

Palmate. — ^Leaf  segments  or  leaflets  radiate  from  a  point  like  the  fingers 
from  the  palm  of  the  hand. 

Panicle. — A  compound  raceme,  as  in  oats. 

Paniculate. — Flowers  in  panicle  or  panicle-like  inflorescence. 

Papilla. — A  small  protuberance. 

Papillose. — With  papillae. 

Pappus. — Bristle-like,  awn-like  scaly  structures  (modified  calyx)  at  the  tip 
of  the  ovary  in  Compositae. 

Parenchyma. — A  tissue  made  up  of  large,  thin-walled  cells  with  rather  large 
intercellular  spaces. 

Parietal. — Pertaining  to  the  wall;  ovules  that  are  attached  to  the  wall  of 
the  ovary  are  said  to  be  parietal. 

Parted. — Separated  into  parts  nearly  to  the  base. 

Parthenocarpy. — A  phenomenon  in  which  the  fruit  matures  without  fertili- 
zation of  ovules. 

Pedicellate. — Possessing  a  pedicel. 

Peduncle. — A  stalk,  either  of  an  individual  flower  or  of  the  inflorescence. 

Pendant. — Hanging. 

Pentamerous  (flower). — Parts  in  fives. 

Perfect  (flower). — Possessing  both  stamens  and  pistils;  hermaphroditic. 

Perennial. — ^Living  from  year  to  year. 

Perianth. — Calyx  and  corolla  taken  collectively,  or  the  external  floral  whorl 
or  whorls. 

Pericarp. — The  ovary  wall,  consisting  of  three  layers:  exocarp,  mesocarp, 
and  endocarp. 

Perigynous. — Calyx,  corolla,  and  stamens  borne  on  a  rim  of  the  receptacle 
such  that  they  appear  on  the  level  with  the  ovary. 

Perisperm. — Nucellus. 

Petaloid.—'Peta.l-]ike. 

Petiole. — The  stalk  of  a  leaf. 


648  BOTANY   OF  CROP  PLAJSJTS 

Plllccm. — That  portion  of  a  vascular  bundle  which  is  largely  concerned  in 
the  transport  of  elaborated  food  material. 

Phyllotaxy. — The  arrangement  of  leaves  upon  a  stem. 

Pileole. — Coleoptile  (which  see). 

Pinnate  (leaf). — Leaflets  arranged  along  the  sides  of  an  axis. 

Pinnalifid. — Pinnately  cleft  to  the  middle  of  the  blade,  or  further. 

Pistillate. — Bearing  pistils  only. 

Placenta. — The  membrane  or  surface  bearing  ovules. 

P/ica/e.— Plaited. 

Plumose. — Plume-  or  feather-like. 

Plumule. — The  first  bud  in  the  young  plant. 

Polyadelphous  (stamens). — Separate,  or  in  more  than  two  groups. 

Polygamo-dicecious. — Bearing  both  perfect  and  imperfect  flowers  on  the 
same  plant,  with  a  tendency  to  become  dioecious. 

Polygamous. — Both  perfect  and  imperfect  flowers  present  on  the  same 
plant. 

Pome. — A  fruit  in  which  the  receptacle  of  the  flower  enlarges,  becomes 
fleshy  and  surrounds  the  carpels,  as  in  apple,  pear,  and  quince. 

Prehensile. — Adapted  for  holding. 

Protandry. — In  which  the  anthers  of  a  flower  shed  their  pollen  before  the 
stigmas  are  receptive. 

Protogyny. — In  which  the  stigmas  of  a  flower  are  receptive  before  its  anthers 
shed  their  pollen. 

Ptibescence. — Fine,  soft  hairs. 

Pubescent. — Covered  with  fine,  soft  hairs. 

Raceme. — Indeterminate  type  of  inflorescence,  in  which  the  pedicels  are 
simple  and  one-flowered. 

Racemose. — Raceme-like. 

Rachilla.— The  axis  of  a  spikelet. 

Rachis. — The  axis  of  a  spike. 

Radical. — Seeming  to  come  from  the  root.  Leaves  arising  from  the  base 
of  stem,  close  to  the  ground  line,  are  said  to  be  radical,  as  contrasted  with 
those  on  the  stem  (cauline). 

Ray. — The  branch  of  an  umbel;  marginal,  ligulate  flowers  of  a  composite 
head. 

Rece  ptacle. — The  end  of  the  axis  to  which  the  floral  organs  are  attached; 
torus. 

Rejlexed. — Turned  back. 

Regular  (flower). — The  parts  of  each  whorl  similar. 

Reniform. — Kidney-shaped. 

Reticulate. — Netted. 

Retrorse. — Turned  back  or  downward. 


GLOSSARY  649 

Rhizome. — Rootstock;  underground  stem,  usually  horizontally  elongated. 
Rotate. — Wheel-shaped. 
Ruderal. — Growing  in  waste  places;  weed. 

Runner. — A  prostrate,  slender,  above-ground  stem,  such  as  in  the  straw- 
berry. 


Saccate. — With  a  sac. 

Sagittate. — Shaped  like  an  arrow-head,  with  the  lobes  turned  downward. 

Salverform  (sympetalous  corolla). — Tubular  with  a  spreading  limb. 

Scabrous. — Rough. 

Scale. — Reduced  leaf  that  appears  lower  on  the  stem  than  the  foliage  leaves. 

Scapose. — Bearing  a  nearly  leafless  flower  stalk  arising  from  the  base  of 
the  plant. 

Schizocarp. — A  dry,  indehiscent  fruit,  of  two  carpels,  each  one-seeded, 
which  split  apart  at  maturity  into  two  halves  or  mericarps. 

Sclerenchymatous.—Compostd  of  cells  that  fit  closely  together  and  have 
thick,  hardened  walls. 

Scutellum. — Morphologically,  the  cotyledon  of  the  grass  embryo. 

Segment. — A  division  of  a  leaf,  fruit  or  flower. 

Seminal. — Belonging  to  the  seed. 

Septum. — Partition  or  dividing  wall. 

Serrate. — With  sharp  teeth  that  point  forward. 

Sessile. — Sitting;  without  a  stalk. 

Sheath. — A  tubular  envelope  about  the  stem,  such  as  occurs  in  the  leaves  of 
grasses. 

Silicle. — Similar  to  a  silique,  except  that  it  is  broader  than  long. 

Silique. — Pod-like  fruit  of  mustards,  dehiscent,  two-valved,  and  with  two 
parietal  placentas;  longer  than  broad. 

Sinuate. — Wavy  along  the  margin. 

Sinus. — The  space  between  two  lobes. 

Spathe. — A  large  bract  or  pair  of  bracts,  subtending  a  spadix  or  flower 
cluster. 

Spatulate. — Shape  of  a  spatula  or  spoon. 

Spicate. — Spike-like. 

Spike. — An  indeterminate  type  of  inflorescence  in  which  numerous  sessile 
flowers  are  borne  on  a  rachis. 

S pikelet. — The  unit  of  inflorescence  in  grasses  and  sedges;  a  small  spike. 

Spinulose. — With  small  spines. 

Squarrose. — With  spreading  parts. 

Staminal. — Of  or  pertaining  to  stamens. 

Staminate  (flowers). — Bearing  stamens  only. 

Staminodeal. — Pertaining  to  staminodia,  i.e.,  abortive  and  sterile  stamens. 


650  BOTANY  OF  CROP  PLANTS 

Standard. — The  large  petal  in  the  flowers  of  Leguminosae. 

Sterile. — Unproductive;  without  the  reproductive  elements. 

Slipitate. — Provided  with  a  stalk  or  stipe. 

Stipules.- — Appendages  at  the  base  of  the  petiole. 

Stipulate. — Bearing  stipules. 

Stolon.— A  trailing  stem,  above  ground,  that  easily  takes  root  at  the  nodes 
when  it  touches  the  ground. 

Stooling. — Production  of  secondary  branches  from  lowermost  nodes,  as  in 
grasses;  tillering. 

Strobile. — Spike-like  pistillate  inflorescence  of  hop;  also  cone-like  group  of 
sporophylls. 

Stylar. — Of  or  pertaining  to  style. 

Stylopodium. — Style-foot.  The  nectariferous  gland  at  the  base  of  the  style 
in  the  Umbelliferous  fruit. 

Suh. — Prefix  signifying  below,  under,  or  almost,  less  than  normal,  in  an 
inferior  degree. 

Subtend. — To  grow  under,  or  be  adjacent  to,  as  a  bract  subtending  a  flower. 

Subulate. — Awl-shaped. 

Sucker. — Rapidly  growing  shoots  from  roots  or  from  stems  underground. 

Superior  (flower). — Ovary  appearing  above  the  other  parts  of  the  flower. 

Sympetaly. — Petals  united. 

Suture.— A  line  of  splitting. 

Sympetalous. — With  the  petals  united  to  form  a  tube. 

Syncarpy. — Condition  in  which  the  carpels  are  united. 

Synconium. — Fleshy  fruit,  in  which  the  receptacle  is  hollow,  and  its  inner 
wall  is  lined  with  numerous  flowers. 

Syngenesiou'; .—^'ith.  the  anthers  united,  as  in  Compositas. 

Tassel. — Staminate  inflorescence  in  corn. 

Tendril. — Slender,  coiled  organ  used  in  climbing. 

Terete. — Cylindrical;  pencil-shaped. 

Ternate. — Arranged  in  threes  or  divided  into  three  divisions. 

Testa. — Seed  coat. 

Tillering. — Production  of  branches  from  the  lowermost  nodes,  as  in  grasses. 

Tomentose.— Covered  with  dense  wool-like  hair. 

Tomentum. — Dense,  woolly  hair. 

Torus. — Receptacle  of  a  flower: 

Translucent. — Partially  transparent. 

Trifoliate. — With  three  leaflets,  as  in  clover. 

Truncate. — As  if  cut  off  squarely  at  the  tip. 

Tuberculate. — Furnished  with  tubercles  or  small  projections. 

Tuberous. — Swollen  and  tuber-like. 

Tubular. — Tube-shaped. 

Turbinate. — Top-shaped. 


GLOSSARY  651 

Umbel. — An  indeterminate  type  of  inflorescence,  in  which  the  pedicels 
arise  from  the  same  point. 
Umbellate. — Umbel-like. 
Umbellet. — Umbel  of  secondary  order. 
Undulate. — With  wavy  margin. 
Utricle. — A  one-seeded  fruit  with  a  bladder-like  covering. 

V abate  (arrangement  of  parts  in  the  bud). — The  segments  meet  with 
their  edges,  without  any  overlapping. 

Valves. — One  of  the  pieces  into  which  a  capsule  splits. 

Venation. — The  arrangement  of  veins. 

Ventral. — On  the  lower  side;  surface  of  member  turned  toward  the  main 
axis. 

Vernation. — Arrangement  of  leaves  in  the  bud. 

Versatile  (anther). — Filament  is  attached  near  middle  of  anther,  so  that 
it  can  readily  turn  in  any  direction. 

Vexillum. — Standard  of  the  flower  in  Leguminosae. 

Viscid. — Sticky. 

Vitta  (pi.  vittae).— Oil  tubes  in  Umbellifer  fruit. 

Wing. — ^Lateral  petal  in  the  flower  of  Leguminosae. 

Whorl. — A  group  of  organs  arranged  in  a  circle  about  a  stem,  and  arising 
from  the  same  node. 

Zygomorphy  (flower).— See  Irregular. 


INDEX 


Abutilon,  506 
Abyssinian  oats,  130 
Achene,  58 
Achillea,  625 
Acrospire,  144 
Adjuki  bean,  423 
Adriatic  figs,  275 
Aegilops,  no 
African  cotton,  5 1 7 

millet,  213 
Agave,  47,  281 
Agropyron  repens,  70,  75 
Agrostis,  81 
Aino  millet,  218,  219 
Alae,  415 
Albumin,  105 
Aleurone  layer,  102 
Alfalfa,  442 

American,  447 

Arabian,  447 

Baltic,  447 

German,  447 

Grimm,  447 

Peruvian,  447 

sickle,  447 

Turkestan,  447 

variegated,  447 

yellow-flowered,  447 
Algae,  62,  63 
Algerian  oat,  131 
Allium,  231 

ascalonicum,  231,  237,  238 

cepa,  232,  237,  240 
bulbellifera,  241 
multiplicans,  241 

fistulosum,  232,  237,  239 

sativum,  236,  237 

schoenoprasum,  231,  232,  237, 


Almond,  410 

bitter,  411 

hard-shelled,  411 

oil,  411 

soft-shelled,  411 

sweet,  411 
Aloe,  229 
Alopecurus,  79 
Alsike  clover,  433,  434 
Althaea,  506 

officinalis,  507 

rosea,  507 
Amarelles,  404 
Amaryllidaceae,  281 
Amelanchier,  366,  367 
American  alfalfa,  447 

cotton,  512,  520 

cranberry,  548 

black  currant,  319,  320 

crabapple,  379 

flowering  currant,  319,  320 

gooseberries,  321 

ivy,  492 

laurel,  543 

plum,  397,  400,  401 

red  raspberry,  357 

upland  cotton,  520 
Amygdalus  persica,  407 
Amyris,  475 
Andropogon,  87,  88 

sorghum,  191 

halepensis,  197 
Angelica,  532 
Angiospermae,  62 
Animated  oats,  131 
Annual  ring,  40 
Annuals,  21,  70 
238         Antennaria,  625 
653 


654 


Anther,  48,  49 
Anthyllis,  429 
Antipodals,  50 
Apium,  533,  538 

graveolens,  539,  540 
rapaceum,  540 

key  to  principal  species  of,  539 

leptophyllum,  539 

petroselinum,  539 
Apple,  367 

American  crab,  379 

common,  379,  381 

family,  366 

flowering  crab,  379 

narrow-leaved  crab,  379 

Siberian  crab,  379 

Soulard  crab,  379,  381 

western  crab,  379,  381 
Apricot,  405 

black,  407 

common,  405 

Japanese,  407 

purple,  407 

Siberian,  407 
Arabian  alfalfa,  447 
Arachis,  hypogoea,  462 
Aragallus,  414 

Arctostaphylos  uva-ursi,  543 
Arnica,  625,  628 

alpina,  600 
Arrhenatherum  elatius,  75 
Artemisia,  625,  628 
Artichoke,  globe,  639 

Jerusalem,  639 
Artificial  gums,  185 
Artocarpus  communis,  252 
Arundinaria,  84 
Ascomycetes,  64 
Asiatic  cotton,  511,  512 
Asparagus,  244 

bean,  422,  458 

falcatus,  244 

"fern"  246 


Asparagus,  laricinus,  244 

lettuce,  632 

medeoloides,  246 

officinalis,  244,  246 

plumosus,  246 

sprengeri,  246 
Aster,  625,  628 
Astragalus,  414 
Atriplex,  296 

hortensis,  299 
Atropa  belladonna,  559 
Auricle,  78 

Australian  tobacco,  600 
Autogamy,  51,  94 
Autumn  wood,  40 
Avena,  88,  123 

abyssinica,  130 

algeriensis,  131 

barbata,  131 

brevis,  130 

byzantina,  130,  131 

fatua,  128,  130,  131 

nuda,  130,  131 

orientalis,  125,  130,  131 

sativa,  89,  125,  126,  128,  130,  131 

sterilis,  131 

strigosa,  130,  131 

wiestii,  131 
Awns,  82 
Azalea,  543 

Bagasse,  227 
Baltic  alfalfa,  447 
Bamboo,  69 
Bambusae,  84 
Banner,  414 

oats,  130 
Banyan,  16 

tree,  267 
Barbe  de  Capuchin,  636 
Bark,  39,  40 
Barley,  72,  88,  89,  135 

black,  145 


655 


Barley,  blue,  145 

fan,  146 

four-rowed,  144 

hooded,  136,  137,  145,  146 

hull-less  Jerusalem,  145 

hybrid,  145 

medium,  137,  143,  145,  146 

Nepal,  145 

peacock,  146 

six-rowed,  144 

two-rowed,  145 
bent,  147 
erect-eared,  147 
naked,  146 
nodding,  147 
Barnyard  grass,  219 

millet,  210,  219,  220 
Basidiomycetes,  64 
Basin,  378 
Bean,  421 

adjuki,  423 

asparagus,  422,  458 

broad,  422,  426,  429 

coffee,  456 

Dolichos,  422 

Dutch  case-knife,  423 

flowering,  423 

hyacinth,  422 

Jack,  422 

kidney,  423,  426 

Lima,  423,  424 

locust,  422 

Mexican,  424 

mung,  423 

painted  lady,  423 

scarlet  runner,  423 

Sieva,  423,  424 

soja,  456 

soy,  422,  455 

velvet,  422 

Windsor,  427,  429 
Beards,  82 
Beet,  common  garden,  300,  310 


Beet,  foliage,  301 
leaf,  301,  312 
ornamental,  301 
pulp,  309 
sea-kale,  312 
seed,  306 

multiple-germ,  306 
single-germ,  306 
silver,  312 
spinach,  312 
sugar,  300,  301 
wild,  301 

Belladonna,  559 

Benincasa  cerifera,  613 

Bergamot,  487 

Beriberi,  206 

Berry,  59 

Berseem,  433 

Beta,  298 

cycla,  312 
maritima,  301 
vulgaris,  300 

Bidens,  625 

Biennials,  21 

Bigarreaus,  403 

Bilberry,  dwarf,  546 
tall  bilberry,  547 
thin-leaved,  544 

Bindweed,  284 

Binomial  system,  64 

Bird's-foot  trefoil,  466 

Bistort,  286 

Bittersweet,  561 

Black  apricot,  405 
barley,  145 
bitter  vetch,  428 
blueberry,  547 
-cap  raspberry,  357 
mulberry,  255,  257 
mustard,  327,  339 
nightshade,  560 
salsify,  635 

Blackberry,  354 


656 


INDEX 


Blackberry,  dewberry,  354 

high-bush,  354 

key  to  principal  species  of,  354 

leafy-cluster,  354 

long-cluster,  354 

loose-cluster,  354 

sand, 354 

white,  354 
Blade,  42,  77 
Blanched  asparagus,  250 
Blastophaga,  grossorum,  271 
Blitum  capitatum,  296 
Blood  orange,  484 
Blue  barley,  145 
Blueberry,  550 

black,  547 

Canada,  546 

high  bush,  547,  550 

low,  546 
black,  546 
bush,  550 
Bokhara,  453 
Boll,  514 
Bonavist,  422 
Brace  roots,  16,  159 
Bracteole,  80 
Bracts,  78 
Brambles,  351 
Bran,  106 

layer,  105 
Brandy,  503 
Brassica,  326,  327 

alba,  327,  340 

arvensis,  339 

campestris,  328,  337 

juncea,  340 

key  to  species  of,  327 

napus,  328,  338 

nigra,  327,  339 

oleracea,  328 

botrytis,  330,  334 
capitata,  329,  331 
caulo-rapa,  330,  333 


Brassica,  oleracea,  gemmifera,  329,  330 
viridis,  329,  330 

rapa,  65,  328,  335 
Bread-fruit,  252 
Breaking,  hemp,  280 
Brebas,  275 
Brewing  process,  149 
British  gums,  185 
Broad  bean,  422,  426,  429 
Broccoli,  334 
Bromus  inermis,  76 
Broom  corn,  88,  196,  197 

-corn  millet,  210,  2r3 
Brown  mustard,  339 
Brush,  99 

Brussel's  sprouts,  329,  330 
Bryophytes,  62 
Buchloe,  70 

dactyloides,  76 
Buckbean,  414 
Buckwheat,  286,  289 

common,  289 
gray,  294 

family,  284 

Japanese,  294 

notch-seeded,  294 

silver  hull,  294 

Tatary,  293 
Bud  variation,  25 
Buds,  23 

accessory,  24 

adventitious,  24 

alternate,  25 

axillary,  24 

branch,  23 

classification  of,  23 

dormant,  23 

flower,  23 

grafting,  23 

lateral,  24 

leaf,  23 

mixed,  23 

opposite,  25 


INDEX 


657 


Buds,  terminal,  24 

supernumerary,  24 
whorled,  25 

Buffalo  bur,  561 
currant,  319 

Bulbs,  32,  229 

Bullaces,  400 

Bulletin  Smyrnas, 

Bundle  scar,  26 

Bupleurura,  530 


275 


Cabbage,  328 

common,  331 

key  to  cultivated  types  of,  329 
types  of  common  head,  332 

lettuce,  633 
Calamondin  orange,  487 
Calendula,  625 
Callirrhoe,  508 
Calyx,  48 
Cambium,  36 

ring,  38 
Camelina,  326 
Campanulaceae,  600 
Canada  blueberry,  66,  546 

crookneck.  squash,  615 

potato,  639 

rice,  206 

thistle,  21,  28 
Canadian  field  pea,  420 
Cane  sugar,  production  of,  228 
Cannabis,  252 

indica,  281 

sativa,  276 
Cantaloupe,  618 
Caper  family,  326 
Capparidaceae,  326 
Caprification,  273 
Caprifig,  269,  272,  276 
Capsaican,  595 
Capsella,  326 
Capsicum,  560,  595 

annuum,  592 
42 


Capsicum,  annuum,  abbreviatum,  595 

acuminatum,  595 

cerasiforme,  595 

conoides,  595 

fasciculatum,  595 

frutescens,  595 

grossum,  595 

longum,  595 
Capsule,  58 
Caraway,  533 

Carbohydrate  synthesis,  46 
Carduus,  625,  628 
Carina,  415 
Carolina  rice,  206 
Carpophore,  532 
Carrot,  533 

family,  530 
Carum,  533 
Caryopsis,  83 
Catawba  grape,  501 
Catjang,  458 
Cat-tail  millet,  213 
Cauliflower,  330,  334 
Cavity,  378 
Cayenne  pepper,  595 
Celeriac,  540 
Celery,  540 
Cell,  4 

as  unit  of  structure,  5 

of  plant  activity,  5 
Cell  sap,  6 

wall,  6,  8 
Celluloid,  526 
Central  cylinder,  17 
Cercocarpus,  348 
Cereals,  87 

key  to  groups  (genera)  of,  87 

small-grain  seedlings  of,  88 
Chaetochloa,  88,  210,  211 
italica,  211,  216,  218 

key  to  principal  types  of,  218 

maximum,  218 

moharium,  219 


658 


Chaetochloa,  viridis,  211,  219 
Chard,  312 
Charlock,  339 
Chasmogamy,  82 
Chenopodiaceae,  296 

key  to  principal  genera  of,  297 
Chenopodium,  297 
Cherry,  401 

sour,  403 

sweet,  402 

tomato,  587,  590 
Chicasaw  plum,  401 
Chick  pea,  467 
Chicory,  628,  635,  636 
Chilean  strawberry,  363,  364 
Chilli  con  came,  596 
Chinese  cotton,  517 

mustard,  340 

pear,  384,  385 
Chiogenes  hispidula,  543 
Chives,  237,  238 
Chlorophyceae,  63 
Chloroplastids,  8 
Chromoplastids,  8 
Chrysanthemum,  625,  628 
Chrysothamnus,  625 
Ciboule,  237,  239 
Cicer  arietinum,  467 
Cichorium,  628 

endiva,  635,  636 

intybus,  635,  636 
Cider,  383 
Cinque-foil,  348 
Citrange,  489 
Citron,  480,  622,  623 
Citrullus,  610,  622 

vulgaris,  623 
Citrus,  476 

aurantifolia,  480,  483 

aurantium,  480,  487 

bergamia,  487 

grandis,  480,  485 
ichangensis,  487 


Citrus,  key  to  principal  species  of,  479 

limonia,  479,  481 

medica,  479,  480 

mitis,  487 

nobilis,  480,  485 
deliciosa,  485 
unshiu,  485 

sinensis,  480,  484 
Cive,  237,  238 
Cladophylls,  244 

Classification  and  naming  of  plants,  60 
Cleistogamy,  82 
Close  pollination,  51 
Clover,  66,  432 

Alsike,  433,  434 

Berseem,  433 

crimson,  433,  43S 

Dutch,  433 

hop,  442,  449 

giant,  453 

Italian,  435 

Japan,  465 

Ladino,  434 

mammoth,  433.  439>  44i 

meadow,  441 

medium  red,  441 

Persian,  433 

purple,  436 

red,  433.  43^ 

scarlet,  433,  435 

Shaftal,  433 

spotted  bur,  442,  449 

Swedish,  433,  434 

sweet,  452 

toothed  bur,  442,  452 

white,  433,  441 

zigzag,  433,  441 
Cloudberry,  350 
Club  mosses,  62 

wheat,  III,  112,  IT4 
Cob,  163 
Coffee  bean,  456 
Coleanthus,  81 


INDEX 


659 


Coleoptile,  104 
Coleorhiza,  10,  103 
Collard,  329,  330 
Collodion,  526 
Colocynth,  622 
Columnar  epithelium,  104 
Commissure,  532 
Common  apple,  379,  381 

apricot,  405 

barnyard  grass,  210 

bread  wheat,  in,  112,  113,  114 

buckwheat,  289 

eggplant,  586 

fig,  269,  275 

gray  buckwheat,  294 

hop,  33 

millet,  219 

onion,  232,  237 

pear,  384,  385 

six-rowed  barley,  144 

sugar  beet,  300,  310 

sweet  pea,  432 

wheat,  65,  III,  112,  114 
Companion  cells,  35 
Compass  plant,  632 
Composite  family,  625 
Compositae,  625 

key  to  important  genera  of,  628 
Concord  grape,  501 
Conium,  532 
Convolvulacese,  554 

key  to  important  genera  of,  555 
Convolvulus,  554 
Cordelia  figs,  276 
Corchorus  capsularis,  281 

olitorius,  281 
Core  line,  377 
Coriander,  533 
Corinth  currants,  501 
Cork  cambium,  38 

tissue,  38 
Corms,  32 
Corn,  157 


Corn,  dent,  178,  180 

flint,  178,  180 

fodder,  185 

oil,  184 

pod,  178,  180 

pop,  178,  180 

soft,  178,  180 

starchy  sweet,  178,  180 

sweet,  178,  180 

starch,  184 

stover,  186 

xenia  in,  172 
Corolla,  48 
Coronilla,  429 
Cortex,  17 
Corymb,  56 
Cos  lettuce,  633 
Cotoneaster,  366 
Cottolene,  524 
Cotton,  508 

African,  517 

American,  512 

Asiatic,  511,  512 

Chinese,  517 

Egyptian,  510 

Guatemalan,  512 

Nankin,  517 

Red  Peruvian,  517 

Sea  Island,  520 

types  and  varieties  of  American,  521 

Upland,  510,  520 

WUd,  520 
Cottonseed  hulls,  524 

meal,  524 

oil,  524 
Couloure  of  Muscat  grape,  498 
Cowberry,  550 
Cowpea,  460 
Crab-apple,  American,  379 

flowering,  379 

narrow-leaved,  379 

Siberian,  379 

Soulard,  379,  381 


66o 


INDEX 


Crab-apple,  western,  379,  381 
Cranberry,  548 

American,  548 

European,  544 

large,  548 

mountain,  550 

small,  548,  549 

types  of,  549 
Crataegus,  366,  367 
Creeping  snowberry,  543 

wintergreen,  543 
Crimson  clover,  433,  435 
Cross  pollination,  52 

artificial,  95 
Crown  vetch,  429 
Cruciferae,  323 

key  to  principal  genera  of,  326 
Cucumber,  615,  617,  620 

common  field,  620,  621 

English  forcing,  621 

Jerusalem,  617 

musk,  620 

prickly,  617 

Sikkim,  621 

squirting,  606 

snake,  620 

star,  606,  620 

wild,  606 
Cucumis,  610 

anguria,  617,  620,  622 

dipsaceus,  613 

key  to  principal  species  of,  617 

melo,  617,  618 
var.  acidulus,  620 
cantalupensis,  618 
chito,  620 
dudaim,  620 
flexuosus,  618,  620 
inodorus,  619 
reticulatus,  618 
saccharinus,  618 

moschata,  620 

sativus,  617,  620 


Cucumis,  sativus,  anglicus,  621 

Sikkimensis,  621 
Cucurbit,  606 
Cucurbita,  610,  612 

key  to  important  species  of,  612 

maxima,  612,  613 

moschata,  612,  613 

pepo,  612,  613 

ovipera,  613 

Cucurbitaceae,  606 

key  to  principal  genera  of,  610 
Culms,  72 

Currant  tomato,  587 
Currants,  American  black,  319,  320 
flowering,  319,  320 

Buffalo,  319 

European,  black,  319,  320 

golden,  319 

Missouri,  319 

red,  320 

white,  320 
Cushaw,  612,  615 
Cuticle,  44 
Cutting  lettuce,  633 
Cyanophyceae,  63 
Cyclanthera,  608 
Cydonia,  388 

oblonga,  388 
varieties  of,  388 
Cymopteris,  532 
Cynara  scolymus,  639 
Cyperace£e,  85 
Cyphomandra  betacea,  592 
Cypress  vine,  554 
Cytase,  142 
Cytoplasm,  6 

Dahlia,  625 

Dakota  vetch,  429 

Damson,  400 

Dandelion,  628 

Dangleberry,  547 

Danish  ball  head  cabbages,  332 


INDEX 


66i 


Datura,  559 
Daucus,  533 

carota,  533 

varieties  of,  535 
Delaware  grape,  501 
Dent  corn,  178,  180 
Dermatogen,  17 
Dewberry,  355 

blackberry,  354 

key  to  principal  species  of,  356 

northern,  356 

Pacific  Coast,  352 

southern,  356 

western,  356 
Dextrins,  185 
Diastase,  142 
Dichogamy,  169 
Dicot  stem,  33 

stem,  growth  in  thickness  of,  38 
Dicotyledones,  63 
Dimorphism,  292 
Dioscorea  batatas,  556 
Dioscoreaceae,  556 
Disk  flowers,  627 
Distichlis,  55 
Dock,  284 
Dolichos  bean,  422 
Domestic  onions,  243 
Double  fertilization,  53 
Dracaena,  229 
Dried  apples,  383 
Drosera,  47 

Drumhead  cabbages,  332 
Drupe,  393 
Drupaceae,  391 
Duboisia  hopwoodii,  600 
Duckweed,  2 
Dukes,  403 
Durra,  196,  197 

Durum  wheat,  89,  in,  112,  113 
Dutch  case-knife  bean,  423 

clover,  433 
Dwarf  bilberry,  546 


Dwarf  broom  corn,  200 

purple  eggplant,  587 
Dye-weed,  414 

Ear,  162 

Early  or  forcing  radishes,  243 
Earth  apple,  639 
Ecballium  elaterium,  606 
Echinochloa,  88,  210 

crus-galli,  210,  219,  220 

frumentacea,  210,  220 
Echinocystis  lobata,  606 
Ectoplasm,  6 
Edible-podded  pea,  418 
Egg  nucleus,  50 
Eggplant,  585 

common,  586 

dwarf  purple,  587 

snake,  587 
Egyptian  cotton,  510 

onions,  241,  242 

millet,  213 
Eichhornia  speciosa,  16 
Einkorn,  85,  no 
Eleusine  coracana,  210 
Elodea,  29 
Embryo,  96 

sac,  so 
Emmer,  89,  in,  112,  113 
Endive,  636 
Endocarp,  58 

Endodermis,  17,  57,  96,  102 
English  currants,  501 
Entire  wheat,  108 
Epiblast,  104 
Epidermis,  34 
Epigasa  repens,  543 
Epiphyte,  28 
Episperm,  loi 
Equisetales,  64 
Erect-eared  barley,  147 
Ericaceae,  543 
Erigeron,  625,  628 


662 


INDEX 


Erinocyce  figs,  275 
Eriogonum,  285,  286 
Eryngium,  530 
Euchlaena  mexicana,  18 r,  182 
European  black  currant,  319,  320 

cranberry,  544 

gooseberries,  321 

raspberry,  357 

strawberry,  363,  364 
Eurotia,  297 

Evergreen  or  fire  thorn,  366 
Everlasting  pea,  432 
Exocarp,  58 
"Eyes,"  31 

Fagopyrum,  286 

emarginatum,  294 

tataricum,  293 

vulgare,  289 
False  flax,  326 

Solomon's  seal,  21 
Fan  barley,  146 
Farkleberry,  543 
Fennel,  533 
Fenugreek,  467 
Fermentation,  150 
Fern  plants,  62 
Fertilization,  52 
Festuca  ovina,  79 

pratensis,  76 
Fiber  flax,  473 

of  cotton,  514 
Ficus,  267 

aurea,  267,  268 

benghalensis,  267 

brevifolia,  268 

carica,  268,  269 

elastica,  252 

religiosa,  267 
Field  cucumber,  621 

pea,  418,  420 
Fig,  267 

Adriatic,  275 


Fig,  common,  269,  275 

Cordelia,  276 

Erinocyce,  275 

Golden,  267 

Mission,  275 

San  Pedro,  275 

Smyrna,  275 

wasp,  271 

wild,  276 
Filament,  48 
Filicales,  64 
Finger  millet,  210 
First  patent,  108 
Five-finger,  348 
Flat  Dutch  cabbages,  332 

onions,  241 

-podded  pea,  432 
Flax,  48,  470 

family,  469 

fiber,  473 

large-seeded,  473 

Sicilian,  473 

small-seeded,  473 
Fleabane,  625,  628 
Flint  corn,  178,  180 
Flour,  kinds  of,  108 
Flower,  apetalous,  55 

complete,  55 

hermaphroditic,  55 

incomplete,  55 

naked,  55 

perfect,  55 

pistillate,  55 

staminate,  55 

symmetry  of,  53 
Flowering  bean,  423 

crabapple,  379 

raspberry,  254 
Flowers,  48 

incomplete,  55 

parts  of  representative,  48 
Fly  oats,  131 
Foeniculum,  533 


INDEX 


663 


Foliage  beet,  310 
Follicle,  58 
Forage  crops,  186 
Foreign  onions,  243 
Fortunella,  476,  487 

crassifolia,  489 

hindsii,  489 

japonica,  489 

margarita,  488 
Four-rowed  barley,  144 
Foxberry,  550 
Foxtail  millets,  211,  216,  219 

grass,  211 
Fragaria,  358 

californica,  363 

chiloensis,  363,  364 

glauca,  363 

vesca,  363,  364 

virginiana,  363 
Fraxinus,  551 
Fruits,  kinds  of,  58 

dehiscent,  58 

dry,  58 

fleshy,  59 

indehiscent,  50 
Fungi,  62 
Furrow,  100 
Fusarium,  570 

Gall  flowers,  271 
Garden  pea,  4181 

lemon,  620 

radish,  341 

tomato,  590 
Garlic,  236,  237 
Gaultheria,  543 
Gaylussacia,  543,  545,  547 

brachycera,  547 

dumosa,  547 

frondosa,  547 

key  to  North  American  species  of, 
547 

resinosa,  547 


Gaylussacia,  ursina,  547 
Geitonogamy,  51 
Generative  nucleus,  50 
Genista,  414 
Geotropism,  73 
German  alfalfa,  447 
celery,  540 
millet,  218,  219 
Gherkin,  622 
Giant  clover,  453,  563 
Girasole,  639 
Gleditsia,  414 
Gliadin,  105 
Globe  artichoke,  639 

onions,  241 
Globulin,  105 
Glucose,  184 
Glume,  flowering,  80 
Glumes,  79,  80 
Gluten,  102,  106,  1 55 

meal,  186 
Glutenin,  106 
Glycyrrhiza,  414 
Golden  currant,  319 
fig,  267 

wonder  millet,  218,  219 
Goldenrod,  625 
Goober,  462 
Gooseberry  family,  316 

gourd,  617 
Gooseberries,  321 
American,  321 
European,  321 
Goosefoot,  296 

family,  296 
Goose  wheats,  113 
Gossypium,  508 

barbadense,  519,  520 
hirsutum,  517,  518,  520 
Gossypol,  524 
Gourd,  610,  613 
family,  606 
gooseberry,  617 


664 


INDEX 


Gourd,  winter,  615 
Grafting,  36 
Graham  flour,  108 
Grain,  83 

coats,  96 
Graminea;,  69 
Granules,  8 
Grape,  492 

Catawba,  501 

Concord,  501 

Delaware,  501 

family,  491 

Muscat,  498 

Niagara,  501 

northern  fox,  499,  500 

Old  World,  499 

raisin,  499,  501 

river  bank,  499,  500 

sand,  499,  500 

southern  fox,  499,  500 

sugar,  185 

summer,  499,  500 

wine,  499,  501 
Grapefruit,  485 
Grass  family,  69 

awnless  brome,  76 

bunch,  76 

buffalo,  70,  76 

quack,  75 

rice-cut,  70 

tall  oat,  75 
Grasses,  bulbous,  75 

rhizome-bearing,  75 

stoloniferous,  76 

tufted,  76 
Greasewood,  297 
Green  asparagus,  250 

foxtail,  211,  219 

gages,  398 
Green-weed,  414 
Grimm  alfalfa,  447 
Griottes,  404 
Groove,  100 


Grossulariaceae,  316 
Ground  meristem,  34 
Growing  point,  57 
Guard  cells,  45 
Guatemalan  cotton,  512 
Guinea  squash,  585 
Gumbo,  527 
Gums,  artificial,  185 

British,  185 
Guncotton,  525 
Gymnospermae,  62 

Hackling,  hemp,  280 
Hairs,  basal,  92 
Hairy  vetch,  427,  430 
Halophyte,  296 
Head,  56 

lettuce,  633 
Hearts,  403 
Heath  family,  543 
Hedysaras,  415 
Helianthus,  628 

tuberosus,  639 
Hemp,  252,  276 

sisal,  281 

tow,  280 
Hennequin,  281 
Hepaticse,  64 
Herb,  2 

Hesperidium,  478 
Heterostyly,  292 
Hibiscus,  506 

esculentus,  507,  527 

syriacus,  508 
High -bush  blackberry,  354 

blueberry,  547,  550 
Hog  millet,  213 
Hollyhock,  508 
Homalocenchrus,  70,  81 
Homogamy,  169 
Honduras  rice,  206 
Hooded  barley,  136,  137,  145,  146 
Hop,  2,3,  252 


INDEX 


66s 


Hop,  clover,  442,  449 
-meal,  264 
-tree,  475 
Hordeum,  88,  135 

distichon,  135,  136,  137,  143,  145 
erectum,  147 
nudum,  146 
nutans,  146,  147 
zeocriton,  146 
spontaneum,  148 
vulgare,  144, 
coeleste,  145 
coerulescens,  145 
hexastichon,  136,  137,  143,  144, 

146 
intermedium,  137,  143,  145,  146 
nigrum,  145 
pallidum,  143,  145,  146 
trifurcatum,  136,  137,  145,  146 
Horse  millet,  213 

nettle,  560 
Horseradish,  345 
Horsetails,  62 
Hortulana  plum,  400 
Hosackia,  429 
Hubbard  squash,  614 
Huckleberry,  547 
black,  547,  sso 
blue,  546,  S47 
box,  547 
bush,  547 
Carolina,  547 
dwarf,  547 
family,  543 
high  bush,  547 
southern  black,  544 
swamp,  547 
Hull-less  Jerusalem  barley,  145 

oats,  130 
Humulus,  252,  258 
japonicus,  265 
lupulus,  258 

neomexicanus,  265 


Hungarian  millet,  219 

vetch,  430 
Husk  tomato,  592 
Hyacinth,  229 

bean,  422 
Hyaloplasm,  6 
Hybrid  barley,  145 
Hydrocotyle,  530 
Hypocotyl,  57,  104 

Ichang  lemon,  487 
Imperatrice  plums,  399 
Incomplete  flowers,  55 
Indian  corn,  88 

millet,  213 

mustard,  340 

tobacco,  600 
India  rubber  plant,  252 
Inflorescence,  determinate  or  cymose,  56 

indeterminate  or  racemose,  56 

scar,  26 

simple,  56 
Integuments,  50 
Intercellular  spaces,  44 
Internodes,  72 

Intracalicary  organs,  of  cotton,  513 
Involucre,  of  cotton,  512 
Ipomoea,  554,  555 

batatas,  555 

bona-nox,  554 

pandurata,  554 

purpurea,  554 
Italian  clover.  435 

Jack  bean,  422 
Japan  clover,  465 

ivy,  33 

millet,  213 

rice,  206 
Japanese  apricot,  407 

barnyard  millet,  210,  220 

buckwheat,  294 

hop,  265 


666 


Japanese  pear,  384,  385 

or  pot-herb  mustard,  340 
plum,  400 

Jasminium,  551 

Jerusalem  artichoke,  628,  639 
cucumber,  617 

Jessamine,  551 

Jimson-weed,  560 

Jumbos,  464 

Juncaceae,  85 

Jute,  281 

Kafir,  196,  197 

Kale,  329,  330 

Kalmia,  543 

Keel,  415 

Kidney  bean,  433,  424 

vetch,  429 
King  orange,  485 
Kinkan,  487 
Kinnikinic,  543 

Kleinwanzlebener  sugar  beet,  308 
Knaurs,  553 
Knotberry,  350 
Knotweed,  284,  286 
Kochia,  297 
Koeleria,  79 
Kohlrabi,  330,  333 
Kowliang,  197 
.Kuhnia,  627 
Kumquat,  487 

Hongkong  wild,  489 

Marumi,  489 

Meiwa,  489 

Nagami,  488 

oval,  488 

round,  489 

Lablab,  422 
Labrador  tea,  543 
Lactuca,  628 
sativa,  629 

angustana,  632 


Lactuca,  sativa,  capitata,  633 
intybacea,  633 
romana,  633 

scariola,  630 
Ladino  clover,  434 
Lagenaria  vulgaris,  613 
Lamb's  quarters,  296 
Lamella,  middle,  375 
Lamina,  77 
Large  cranberry,  548 

leaf  tomato,  590 

-seeded  flax,  473 
Lathyrus,  414 
Lawn  grass,  70 
Layering,  316 
Leaf,  beet,  301,  312 

floral,  2 

foliage,  2 

scale,  2 

scar,  26 

stalk,  42 
Leaflets,  44 

Leafy-cluster  blackberry,  354 
Leaves,  42 

compound,  44 

development  of,  42 

foliage,  42 

kinds  of,  42 

parts  of,  42 

simple,  44 

structure  of,  44 
Leek,  232,  236,  238 
Ledum,  543 
Legume,  413 
Leguminosse,  413 

key  to  principal  genera  of,  416 
Lemma,  80 
Lemon,  481 

Ichang,  487 
Lenticel,  27 
Lepidium,  326 
Lespedeza  striata,  465 
Lettuce,  628 


INDEX 


667 


Lettuce,  asparagus,  632 

cos,  633 

cutting  or  cut-leaved,  633 

garden,  629 

head  or  cabbage,  633 

key  to  types  of,  632 
Leucoplastids,  8 
Lianas,  33 
Licorice,  414 
Lignin,  36 

Ligulate  flowers,  627 
Ligule,  78 
Liguliflorae,  627 
Ligustrum,  551 
Lilac,  SSI 
Liliaceae,  229 
Lilium,  229 
Lily,  229 

family,  229 
Lima  bean,  423,  424 
Lime,  483 
Limequat,  483 
Linaceae,  469 
Linen,  473 
Linoleum,  473 
Linseed  oil,  473 
Linum,  470 

catharticum,  469 

usitatissimum,  470 
Llanos,  69 
Liverworts,  62 
Lobelia  inflata,  600 
Lobfigs,  27s 
Locks,  514 
Loco,  414 
Locust,  414 

bean,  422 
Lodicules,  80 
Lodging,  72 
Loganberry,  358  . 
Lombard  plums,  399 
Long-cluster  blackberry,  354 
Loose-cluster  blackberry,  354 


Lotus  corniculatus,  466 
Low  black  blueberry,  S46 
blueberry,  546 
bush  blueberry,  sso 
Luffa,  613 
Lupines,  465 
Lupinus,  46s 
Lupulin,  264 

glands,  264 
LupuHne,  266 
Lycium,  559 
Lycopersicum,  587 

esculenfum,  cerasiforme,  587 
grandifolium,  587,  s88 
pimpinellifolium,  587,  588 
pyriforme,  587 
validum,  587 
vulgare,  S9o 
Lycopodiales,  64 


Macaroni,  118 

wheats,  113 
Macounastrum,  284 
Maiz  de  coyote,  179 
Maize,  88,  iS7 
Male  nuclei,  so 
Mallow  family,  505 
Malting,  149 
Malus,  366,  367 

angustifolia,  379 

baccata,  379 

coronaria,  379 

floribunda,  379 

ioensis,  379,  381 

key  to  principal  species  of,  379 

soulardi,  379,  381 

sylvestris,  379,  381 
Malva,  507,  508 
Malvaceae,  50s 

key  to  important  genera  of,  508 
Mamme,  272 
Mammoni,  272 


668 


INDEX 


Mammoth  clover,  433,  439,  441 

pumpkins  and  squashes,  615 
Mandarin  orange,  485 
Mand's  wonder  forage  plant,  213 
Mane  oats,  130 
Mangels,  313 
Mangel- wurzels,  313 
Man-of-the-earth,  554 
Marblehead  squash,  614 
Marigold,  625 
Marrow  squashes,  614 
Marsh  mallow,  506 
Massecuite,  227 
Mayberry,  358 
Mazzards,  402 
Meadow  clover,  441 
fescue,  76 
foxtail,  79 
Meadows,  69 
Mealiness,  in  apple,  375 
Medicago,  441 

arabica,  442,  449 

inermis,  451 
falcata,  443,  447 
hispida,  442,  452 
confinis,  452 
denticulata,  452 
reticulata,  452 
key  to  principal  species  of,  442 
lupulina,  442,  449 
media,  447 
sativa,  442,  447 
polia,  448 
Medics,  441 
Mediterranean  oats,  130 

orange,  484 
Medium  barley,  137,  143,  145,  146 

red  clover,  441 
Medulla,  18 
Medullary  ray,  35,  39 
Megarhiza  calif ornica,  610 
Melilot,  453 
Melilotus,  452 


Melilotus,  alba,  453,  454 
altissima,  454 
gracilis,  454 
indica,  454 
officinalis,  453,  454 
speciosa,  454 
Melon  apple,  620 

pear,  561 
Melons,  618 

cucumber,  620 
Dudaim,  620 
Mango,  620 
netted,  618 
orange,  620 
pineapple,  618 
pomegranate,  620 
Queen  Anne's  pocket,  620 
snake,  618 
winter,  619 
Mendelism,  421 
Mendel's  law,  421 
Mericarp,  532 
Meristem  tissue,  33 
Mesembryaceae,  299 
Mesocarp,  58 
Mexican  bean,  424 

grass,  182 
Micrampelis,  608 
Micropyle,  50,  57 
Middlings,  108 
Millet,  88,  210 
African,  213 
Aino,  218 
barnyard,  210,  219 
broom-corn,  210,  213 
Egyptian,  213 
foxtail,  211,  216 
German,  218 
Golden  Wonder,  218 
Hog,  213 
Horse,  213 
Hungarian,  219 
Indian,  213 


INDEX 


669 


Millet,  Japan,  21  3 

Japanese  barnyard,  210,  220 

key   to   principal    economic   types 

(species)  of,  210 
pearl,  211 
proso,  210,  213 
Siberian,  218 
true,  210 
Milo,  88,  196,  197 
Mirabelles,  400 
Mission  figs,  275 
Missouri  currant,  319 
Monocot  stems,  39 
Monocotyledones,  62 
Monolepis,  297 
Moon-flower,  554 
Mooting,  73 
Moraceae,  252 
Morellos,  404 
Morning  glory,  33 

family,  554 
Morus,  252,  253 
alba,  255 

tartarica,  255 
venosa,  255 
key^,to  principal  species  of,  255 
multicaulis,  256 
nervosa,  256 
nigra,  255,  257 
rubra,  255,  257,  258 
Moss  plants,  62 
Mountain  ash,  366 
bramble,  351 
cranberry,  550 
mahogany,  348 
sorrel,  284 
spinach,  299 
timothy,  223 
tobacco,  600 
Mulberry,  252,  253 
black,  25s,  257 
family,  252 
paper,  254 


Mulberry,  red,  255,  257,  258 
Russian,  255 
white,  255 
Mule  flowers,  271 
Multiplier  onions,  242 
Multipliers,  241 
Mung  bean,  423 
Muscat  grape,  498 
Musci,  64 

Musk  cucumber,  620 
Muskmelon,  618 
Mustard,  327 

black,  327,  339 

brown,  339 

Chinese,  340 

family,  323 

Indian,  340 

Japanese,  340 

pot-herb,  340 

white,  327,  340 
Myrobalan  plum,  400 
Myxomycetes,  63 

Naked  oats,  130 

wheats,  in,  112 
Nankin  cotton,  517 
Nardus,  81 
Narbonne  vetch,  429 
Narrow-leafed  crab-apple,  66,  379 

leaved  vetch,  428 
Navel  orange,  484 
Nectaries,  of  cotton,  512 
Nectarine,  410 
Nepal  barley,  145 
Nepenthes,  47 
New  Zealand  spinach,  299 
Niagara  grape,  501 
Nicotiana,  560,  596 

alata,  600 

glauca,  596 

persica,  600 

quadrivalvis,  600 

rustica,  600 


670 


INDEX 


Nicotiana,  tabacum,  597 

tomentosa,  596 

wigandioides,  596 
Nodding  barley,  147 
Node,  22 
Nodes,  72 

Non-saccharine  sorghums,  196 
Northern  dewberry,  65,  356 

fox  grape,  499,  500 
Nucellus,  50,  102 
Nucleoli,  6 
Nucleus,  6,  8 
Nurse  crop,  149 

Oats,  88,  89,  123 
Abyssinian,  130 
Algerian,  131 
animated,  131 
banner,  130 

flyj  131 

hull-less,  130 

mane,  130 

Mediterranean,  130 

naked,  130 

panicle,  130 

rough, 131 

short,  130 

side,  130 

single,  126 

sterile,  131 

Tatarian,  130 

twin,  126 

wild,  130 
Ochrus,  432 
Ocrea,  284 
Oil  cake,  473 

meal,  473 
Okra,  527 

Old  World  plums,  397 
Oleaceae,  551 
Olea  europooea,  551 
Oleomargarine,  524 


Olive,  SSI 

family,  ssi 
Onion,  231,  240 

common,  232,  237 

Egyptian,  241,  242 

multiplier,  241,  242 

perennial  tree,  243 

potato,  241 

top,  241,  242 

tree,  241,  242 

Welsh,  231,  239 
Onions,  types  of,  241 

composition  of,  243 

uses  of,  244 
Onobrychis  viciaefolia,  465 
Ophioglossales,  64 
Orache,  299 
Orange,  blood,  484 

Calamondin,  487 

common,  484 

king,  48s 

faiandarin,  485 

Mediterranean,  484 

navel,  484 

Satsuma,  48s 
,  Seville,  487 

sour,  487 

Spanish,  484 

sweet,  484 

trifoliate,  489 

Unshiu,  485 
Organs,  4 

absorptive,  4 

reproductive,  4 
Ornamental  beet,  301 
Ornithopus  sativus,  465 
Oryza,  81,  87,  88 

glutinosa,  204 

granulata,  206 

oflBcinalis,  206 

sativa,  200,  206 
utilissima,  206 
communis,  206 


INDEX 


671 


Oryza,  sativa,  minuta,  206 
Osage  orange,  252 
Ovary,  48 

inferior,  54 

superior,  54 

wall,  loi 
Ovules,  48,  so 
Oxypolis,  530 
Oxyria  digyna,  284 
Oyster  plant,  633 

Spanish,  635 

Pacific  Coast  dewberry,  352 
Painted  lady  bean,  423 
Palea,  80 
Palet,  80 

Palisade  tissue,  44 
Panicle,  56,  79 

oats,  130 
Panicum,  210 

miliaceum,  210,  213 
compactum,  215 
contractum,  215 
effusum,  215 
Papaveraceae,  326] 
Paper  mulberry,  252,  254 
Pappus,  627 

Papyrus  papyrifera,  252,  254 
Parsley,  539 
Parsnip,  536 
Parthenocarpy,  374 
Parthenocissus,  492 
Pastinaca,  533 

sativa,  536 
Pasture  crop,  149 
Patent  flour,  108 
Patanas,  69 
Pea,  417 

chick,  467 

common  sweet,  432 

edible-podded,  418 

family,  413 

everlasting,  432 


Pea,  field,  418,  420 

flat-podded,  432 

garden,  418 

perennial,  432 

shelling,  418 

sugar,  418 

Tangier,  432 

wild,  432 
Peach,  407 
Peacock  barley,  146 
Peanut,  462 

butter,  464 

meal,  465 

oil,  465 
Pear,  384 

Chinese,  384,  385 

common,  384,  385 

Japanese,  384,  385 

sand,  384,  385 

tomato,  587 
Pearl  barley,  149 

miUet,  211 
Peepul  tree,  267 
Pencilaria,  213 
Pennisetum,  88,  210 

spicatum,  an 
Penny  cress,  326 
Pepino,  561 
Pepo,  608 
Pepper,  592 

Cayenne,  595 

Tabasco,  595 

vine,  492 
Perennial,  20,  70 

pea,  432 

tree  onions,  243 
Perianth,  49 
Periblem,  17 
Pericarp,  loi 
Pericycle,  17 
Peridrigon  plums,  399 
Perisperm,  102 
Perpetual  strawberry,  363,  364 


672 


Persian  clover,  433 

tobacco,  600 
Persicaria,  286 
Peruvian  alfalfa,  447 
Petals,  48 
Petiole,  42 
Petunia,  559 
Phaeophycese,  63 
Phaseolus,  421 

angularis,  423 

aureus,  423 

key  to  principal  species  of,  423 

lunatus,  423,  424 
macrocarpus,  424 

multiflorus,  423 

vulgaris,  423,  426 
nanus,  426 
Phleum,  222 

alpinum,  223 

pratense,  222 
Phloem,  18,  35 

elements,  functions  of,  36 

parenchyma,  35 
Photosynthesis,  46 
Phycomycetes,  64 
Phylloxera,  499 
Phylogeny,  83 
Physalis,  559 
Pickles,  621 
Pie  plant,  286 
Pileole,  104 
Pistil,  48,  51 

Pistillate  inflorescence,  55 
Pisum,  416,  417 

sativum,  418 
Pitcher  plants,  47 
Pitching,  150 
Pith,  18,  39 
Placenta,  50 
Placentation,  53 
Plant  body,  i 

fundamental  internal  structure  of,  4 

cell,  4 


Plant  body,  cell,  discovery  of,  4 
structure  of,  6 

nomenclature,  64 
Plastids,  chloroplastids,  8 

chromoplastids,  8 

leucoplastids,  8 
Plerome,  17 
Plum,  American,  397,  400,  401 

Chicasaw,  401 

family,  391 

hortulana,  400 

Japanese,  400 

key  to  principal  species  of,  397 

myrobalan,  400 

old  world,  397 

tomato,  590 
Plumy  asparagus,  246 
Poa  pratensis,  70 
Poaceae,  69 
Pod,  58 

corn,  178,  180 
Polar  nuclei,  50 
Polish  wheat,  in,  112,  113 
Pollen  grains,  48,  52 

mother  cells,  50 

tube,  52 
Pollination,  51 
Polygonaceae,  284 

key  to  principal  genera,  286 
Polygonum,  284 
Pomaceae,  366 

key  to  important  genera  of,  367 
Pome,  366 
Pomelo,  485 
Poncirus,  476,  489 

trifoliata,  489 
Pop  corn,  178,  180 
Poppy  family,  326 
Pot-herb  mustard,  340 
Potamogeton,  29 
Potato,  561 

family,  559 

onions,  241 


673 


Potentilla,  348 
Poulard  wheat,  iii,  112 
Prickly  ash,  475 

cucumber,  617 
Privet,  SSI 
Profichi,  272 
Prophyllum,  80 
Prop  roots,  16,  159 
Proso,  213 

millet,  210 
Protandry,  170 
Protease,  142 
Proteose,  105 
Protogyny,  170 
Protoplasm,  9 
Protoplasmic  membrane,  6 
Protoplast,  6 
Prunes,  398 
Prunus,  394 

americana,  400 

amygdalus,  410 

angustifolia,  401 

armeniaca,  405 

avium,  402 

besseyi,  404 

cerasifera,  400 

cerasus,  402,  403 

cuneata,  404 

dasycarpa,  407 

domestica,  398 

emarginata,  404 

hortulana,  400 

insititia,  399 

key  to  main  groups  of,  394 

mahaleb,  404 

mume,  407 

munsoniana,  401 

nigra,  401 

pennsylvanica,  404 

persica,  407 

pumila,  404 

sibirica,  407 

triflora,  400 
43 


Psedera  tricuspidata,  33 
Pseudomonas  radicicola,  413 
Psilotales,  64 
Ptelea,  475 
Pteridophytes,  62 
Pumpkin,  613 

field,  613 

mammoth,  613 

Valparaiso,  613 ' 
Purple  apricot,  407 

cane  raspberry,  337 

clover,  436 

vetch,  428 
Pyrus,  384 

communis,  384,  385 

serotina  culta,  384,  385 

Quackgrass,  21,  70 
Quamoclit  quamoclit,  554 
Quince,  388 

Rabbit-brush,  625 
Raceme,  56,  78 
Rachilla,  79 
Rachis,  79,  92 
Radicula,  344 

armoracia,  345 

nasturtium-aquaticum,  345 
Radicle,  57 
Radish,  341 

garden,  341 

rat-tailed,  343 

wild,  342 
Ragi  millet,  210 
Raisin  grape,  499,  500 
Raisins,  501 
Raphanus,  341 

caudatus,  343 

raphanistrum,  342 

sativus,  341 
Raspberry,  357 

American  red,  357 

black  cap,  357 


674 


INDEX 


Raspberry,  European  red,  357 

key  to  principal  species  of,  357 

purple-cane,  357 
Rat-tailed  radish,  343 
Ray  flowers,  627 
Receptacle,  49 
Red  cabbages,  332 

clover,  433,  435 

currant,  320 

mulberry,  255,  257,  258 

Peruvian  cotton,  517 
Repeated  germination,  109 
Reproductive  activity,  i 
Retting,  279 
Rheum,  289 

palmatum,  289 

undulatum,  289 
Rhizoctonia,  569 
Rhizomes,  29,  75 
Rhododendron,  543 
Rhodophyceae,  63 
Rhubarb,  286 
Ribes,  americanum,  319,  320 

aureum,  319,  320 

grossularia,  319,  321 

key  to  important  species  of,  319 

nigrum,  319,  320 

oxycanthoides,  319,  321 

rubrum,  319,  320 

vulgare,  319,  320 
Rice,  88,  202 

Canada,  206 

cultivated,  206 

large-kerneled,  206 

small-kerneled,  206 

wild,  206,  207 
River  bank  grape,  499,  500 
Robinia,  414 
Rockmelons,  6i8 
Root  cap,  17 

crown,  157 

hair,  effect  of  external  factors  upon 
development  of,  20 


Root  cap,  structure  of,  20 
-hair  zone,  19 
primary,  10 
sheath,  10,  103 

system,  effect  of  environment  upon 
character  of,  14 
primary,  91 
temporary,  91 
systems,  2,  10 
adventitious,  11 
development  of,  10 
fibrous,  10,  II 
primary,  10 
tap,  14 

temporary,  10 
tubercles,  413 
Roots  adventitious,  11 
air,  16 
classification  of,  based  upon  their 

medium  of  growth,  16 
general  characteristics  of,  15 
length  of  life  of,  21 
seminal,  10 
soil,  16 

structure  of,  16 
tap,  14 
water,  16 
work  of,  14 
Rootstocks,  29,  75 
Rosaceas,  348 

key  to  important  genera  of,  350 
Rose  family,  348 

of  Sharon,  508 
Rough  oats,  131 
Rubus,  350,  353 

argutus,  354,  355 
bernardinus,  357 
chamaemorus,  350 
cuneifolius,  354,  355 
glaucifolius,  357 
idaeus,  357 
invisus,  356 
key  to  groups  of,  353     • 


INDEX 


67s 


Rubus,  leucodermis,  357 

microphyllus,  358 

neglectus,  358 

nigrobaccus,  354 
albinus,  354 
sativus,  354 

occidentalis,  357 

strigosus,  357,  358 

trivialis,  356 

villosus,  354,  356 
roribaccus,  356 

vitifolius,  352,  356,  358 
Rue  family,  475 
Rumex,  284 
Runner,  13,  32,  76,  358 
Rushes,  8s 
Russian  mulberry,  255 

thistle,  47,  296 

vetch,  430 
Rutabaga,  337 
Rutaceae,  475 

kej'  to  important  genera  of,  476 
Rye,  88,  89,  153 

Saccharum  of&cinarum,  225 

Sachs,  177 

Sage,  625,  628 

Sainfoin,  465 

Sake,  207 

Salicornia,  297 

Salsify,  628 

black,  63s 

Spanish,  635 

yellow-flowered,  635 
Salsola,  296 
Saltbush,  296 
Salt-grass,  55 
Salt  wort,  47 
Samara,  551 
Sand  bur,  560 

blackberry,  354 

grape,  499,  500 

pear,  384,  385 


San  Pedro  figs,  275 
Sanicula,  532 
Sarcobatus,  297 
Sarracenia,  47 
Sauerkraut,  332 
Satsuma  orange,  485 
Savannahs,  69 
Savoy  cabbages,  332 
Scales,  78 
Scallop,  613 
Scarlet  clover,  433,  435 

runner  bean,  423 

strawberry,  363 

vetch,  428 
Schizomycetes,  63 
Schizophytes,  63 
Schuster,  84 
Scientific  name,  64 

versus  common  name,  66 

names,  descriptive  nature  of,  66 
Scion,  36 

Scorzonera  hispanica,  635 
Scouring  rushes,  62 
Scutching,  hemp,  280 
Scutellum,  104 
Sea  Island  cotton,  520,  521 
Sca-kale  beet,  312 
Secale,  88,  153 

anatolicum,  155 

cereale,  89,  153 

montanum,  155 
Second  patent,  108 
Secondary  cortex,  38 
Sedges,  85 
Seed  ball,  306 

coats,  57 

germination  of,  59 

leaves,  59 

plant  body,  size  and  form  of,  2 
principal  parts  of,  i 
Seeds,  57 
Seedlings,  57 
Self -fertility,  372 


676 


INDEX 


Self-sterility,  372,  497 
Seminal  roots,  103 
Semolina,  118 
Sepals,  48 
Sequoias,  Giant,  2 
Serradella,  465 
Service  berry,  366 
Setaria,  210 
Seville  orange,  487 
Shaddock,  485 
Shaftal  clover,  433 
Shallot,  237,  238 
Shallu,  196,  197 
Shank,  163 
Shantz,  117 
Sheath,  77 
Sheep's  fescue,  79 
Shelling  pea,  418 
Shepherd's  purse,  326 
Shoot  system,  2 

development  of,  22 
Short  oats,  130 
Shrub,  2 
Siberian  apricot,  407 

crabapple,  379 

millet,  218,  219 

vetch,  430 
Sicilian  flax,  473 
Sickle  alfalfa,  447 
Sicyos  angulatus,  606 
Sicyosperma  gracilis,  610 
Sieva  bean,  423,  424 
Sieve  tubes,  35 
Sikkim  cucumber,  621 
Silage,  186 
Silicle,  325 
Silique,  325 
Silks,  171 
Silo,  186 
Silver  beet,  312 

hull  buckwheat,  294 
Single  oats,  126 
Sisal  hemp,  281 


Sitopyros,  no 
Six-rowed  barley,  144 
Small  cranberry,  548,  549 
Small-seeded  flax,  473 
Smilax,  244 
Smith,  175 
Smother  crop,  149 
Smyrna  figs,  273,  275 
Snake  cucumber,  620 

eggplant,  587 
Soap  weed,  229 
Soft  corn,  178,  180 
Soja  bean,  456 
Solanacese,  559, 

key  to  important  genera  of,  560 
Solanum,  560 

carolinense,  560,  561 

chiloense,  561 

commersonii,  561 

dulcamara,  560,  561 

elaeagnifolium,  560 

immite,  561 

jamesii,  561 

key  to  important  species  of,  561 

maglia,  561 

melongena,  561 
depressum,  587 
esculentinum,  586 
serpentinum,  587 

muricatum,  561 

nigrum,  560,  561 

rostratum,  560,  561 

triflorum,  561 

tuberosum,  560,  561,  562 
Solidago,  625 
Sonchus,  625 
Sophia,  326 
Sophora,  415 
Sorbus,  366 
Sorghum,  88 
Sorghums,  191 

key  to  principal  types,  197 

origin  of,  197 


INDEX 


677 


Sorghums,  uses  of,  199 
Sorgo,  196,  197 
Soulard  crabapple,  379,  381 
Sour  orange,  487 
Southern  dewberry,  356 

fox  grape,  499,  500 
Sow-thistle,  625 
Soy  bean,  456 
Soya,  455 

max,  456 
Spanish  bayonet,  229 

moss,  28 

needles,  625 

orange,  484 

salsify,  635 
Spathe,  234 
Spelt,  89,  III,  112,  113 

wheats,  iii 
Sperm  nuclei,  50 
Spermatophytes,  62 
Sphenophyllales,  64 
Spike  56,  79 
Spikelet,  78,  79,  80 
Spinacea,  298 

oleracea,  298 
Spinach  beet,  312 

common  garden,  300 

key  to  groups  of,  300 

mountain,  299 

New  Zealand,  299 
Spines,  33 
Spiraea,  348 

Spongy  parenchyma,  44 
Spotted  bur  clover,  442,  449 
Spreading  oats,  130 
Spur,  23 
Spurs,  367 
Squash,  610 

Canada  crookneck,  610,  612 

Hubbard,  612,  614 

mammoth  whale,  615 

marblehead,  610,  612,  614 

marrow,  614 


Squash,  summer,  613 

turban,  610,  612,  614 

Valparaiso,  615 
Squirting  cucumber,  606 
Stages,  ripening,  97 
Stamens,  48 

Staminate  inflorescence,  55 
Standard,  414 

broom  corn,  200 

patent,  108 
Star  cucumber,  606,  620 
Starches,  177 
Starchy  endosperm,  103 

sweet  corn,  178,  180 
Strawberry  tomato,  592    . 
Stele,  17 

Stem,  of  dicot,  33 
Stems,  22 

aerial,  2 

classification  of,   based  upon  their 
medium  of  growth,  28 

general  characteristics  of,  26 

structure  of,  33 

underground,  2 

work  of,  41 
Steppes,  69 
Stewart,  167 
Stigma,  48 
Stipules,  42 
Stock,  36 
Stolon,  32 
Stomata,  45 
Stone  crop,  47 
Stooling,  22,  73 
Straight  bread  flour,  108 
Strawberry  blite,  296 

Chilean,  363,  364 

European,  363,  364 

everlasting,  364 

perpetual,  363,  364 

scarlet,  363 

Virginian,  363 

wood,  364 


678 


Streamside  grape,  66 
Streptochaeta,  81,  84 
Sturtevant,  159,  167,  178 
Stylar  canal,  168 
Style,  48 
Stylopodium,  531 
Succory,  635,  636 
Suckers,  160 
Sugar  beet,  300,  301 
Sugar  cane,  225 

pea,  418 
Sultanas,  501 
Summer  figs,  275 

grape,  499,  500 

radishes,  243 

wood,  40 
Sundew,  47 
Sunflower,  625,  628 
Swedes,  337 

Swedish  clover,  433,  434 
Sweet  clover,  452 
white,  454 
yellow,  454 

corn,  178,  180 

orange,  484 

pea,  leaf,  43 

potato,  555 

sorghums,  196 
Swiss  chard,  312 
Synconium,  268 
Synergids,  50 
Systema  Naturae,  61 
Systematic  botany,  60 
Syringa,  551 

Tabasco  pepper,  595 
Tall  bilberry,  547 
Tangelo,  485 
Tangerine,  485 
Tangier  pea,  432 
Tangleberry,  547  ] 
Tansy  mustard,  326 
Tap  root  system,  13 


Taraxacum,  628 

Tares,  429 

Tassel,  55,  162 

Tatarian  oats,  130 

Tatary  buckwheat,  293 

Teas'  weeping  mulberry,  256 

Tempering,  107 

Tendrils,  33 

Teneriffe,  243 

Teosinte,  166,.  181,  182 

Testa,  loi 

Tetragonia  expansa,  299 

Thallophytes,  62 

Thallus,  I 

plants,  62 
Thermopsis,  414 
Thin-leaved  bilberrj^  544 
Thistle,  625,  628 

family,  625 
Thlaspi,  326 
Thorn  apple,  366,  367 
Tillandsia  usneoides,  28 
Tillering,  22,  73,  74 
Timothy,  75,  222 
Tissue,  4 
Tobacco,  596 

Australian,  600 

Indian,  600 

mountain,  600 

Persian,  600 

"wild,"  600 
Tomato,  587 

cherry,  587,  590 

currant,  587 

garden,  590 

husk,  592 

key  to  types  of  cultivated,  59 1 

large  leaf,  590 

pear  or  plum,  587,  590 

strawberry,  592 

tree,  592 

upright,  587,  590 
Toothed  bur  clover,' 442,  452 


INDEX 


679 


Topinambour,  639 
Top  onions,  241,  242 
Torch-wood,  475 
Torus,  49 

Toxylon  pomiferum,  252 
Tracheal  tubes,  36 
Tracheids,  36 
Tragopogon,  628 

porrifolius,  633 

pratensis,  635 
Trailing  arbutus,  543 
Transpiration  stream,  47 
Tree,  2 

onions,  241,  242 

tomato,  592 
Trifoliate  orange,  489 
Trifolium,  66,  432 

alexandrinum,  433 

hybridum,  433,  434 

incarnatum,  433,  435 

key  to  principal  species  of,  433 

medium,  433,  441 

pratense,  433,  436 
perenne,  439 

repens,  433 

suaveolens,  433 
Trigonella  foenum-grcecum,  467 
Tripping,  of  alfalfa  flowers,  444 
Triticum,  88,  91 

cegilopoides,  112,  116 

aestivum,  in,  112,  114,  116 

boeoticum,  112 

capitatum,  n6 

compactum,  in,  112,  114,  116 

dicoccum,  in,  112,  113,  116 
dicoccoides,  114,  115,  116 

durum,  in,  112,  113,  116 

hermonis,  114 

monococcum,  no,  in,  112 

ovata,  no 

polonicum,  in,  112,  113,  116 

spella,  III,  112,  113,  116 

thaoudar,  112 


Triticum,  turgidum,  in,  113,  116 

Tube  nucleus,  50 

Tuberization,  fungus  theory  of,  569 

Tubers,  30,  31 

Tubuliflorse,  627 

Tulip,  229 

Turban  squash,  614 

Turkestan  alfalfa,  447 

Turnip,  65,  335 

common,  335 

Swede,  337 
Turnip-rooted  celery,  540 
Twin  oats,  126 
Two-rowed  barley,  145 

Umbel,  56,  234,  530 
Umbelliferae,  530 

key  to  genera  of  economic  impor- 
tance, 533 
Unshiu  orange,  485 
Upland  cotton,  510,  520 
Upright  tomato,  587,  590 
Utricle,  297 

Vaccinium,  543,  545 

angustifolium,  546,  550 

arboreum,  543 

atrococcum,  547,  550 

caespitosum,  546 

canadense,  66,  546,  550 

corymbosum,  547,  550 

key  to  chief  fruit-bearing  species  of, 
546 

macrocarpon,  546,  548 

membranaceum,  544 

myrtillus,  546 

nigrum,  546,  550 

ovalifolium,  547 

oxycoccus,  546,  549 

'vacillans,  546,  550 

virgatum,  544 

vitis-idaea,  546,  550 
Vacciniaceae,  543 


68o 


Vacuole,  7 

Variegated  alfalfa,  447 
Vascular  bundles,  35 

elements,  35 
Vegetative  activity,  i 
Velvet  bean,  422 
Vetch,  414,  426 

black  bitter,  428 

crown,  429 

Dakota,  429 

hairy,  427,  430 

Hungarian,  430 

kidney,  429 

Narbonne,  429 

narrow-leaved,  428 

purple,  428 

Russian,  430 

scarlet,  428 

Siberian,  430 

villous,  430 

woolly-podded,  429 
Vetchling,  432 
Vexillum,  414 
Vicia,  414,  426 

angustifolia,  428 

atropurpurea,  428 

dasycarpa,  429 

ervilia,  428 

faba,  427,  429 

fulgens,  429 

key  to  important  species  of,  427 

narbonnensis,,  429 

sativa,  427,  429' 

villosa,  427,  430 
Vigna,  458 

catjang,  458 

sequipedalis,  458 

sinensis,  458,  460 
Villous  vetch,  430 
Vilmorin  sugar  beet,  308 
Vine  peach,  620 
Vinegar,  383,  503 
Virginia  creeper,  16,  33 


Virginian  strawberry,  363 
Vitaceae,  491 

key  to  important  genera  of,  492 
Vitis,  492 

aestivalis,  499,  500 

bourguiniana,  501 

labrusca,  499,  500 

riparia,  499,  500 

rotundifolia,  499,  500 

rupestris,  499,  500 

vinifera,  499 

Wakefield  cabbages,  332 
Washingtonia,  532 
Water  cress,  345 

hyacinth,  16 

lily,  29 
Watermelon,  610,  622,  623 

types  and  varieties,  623 
Welsh  onion,  232,  237,  239 
West  Indian  gherkin,  617 
Western  crabapple,  379,  381 

dewberry,  356 
Wheat,  88,  89,  91 

classification  of  the  types  of,  no 

club.  III,  112,  113,  114 

common  bread,  in,  112,  113,  114 

durum,  89,  in,  112,  113 

grain,  microscopic  section,  100 

hard,  106 

naked,  in,  112 

Polish,  III,  112,  113 

Poulard,  in,  112,  113 

soft,  106 

spelt,  in,  112,  113 
White  blackberry,  354 

clover,  433,  441 

currant,  320 

mulberry,  255 

mustard,  327,  340 
Whortleberry,  546 
Wild  barnyard  grass,  210 

beet,  301 


INDEX 


68l 


Wild  cabbage,  328 

cotton,  520 

cucumber,  606 

emmer,  114,  115 

fig,  276 

goose  wheats,  113 

oats,  130 

pea,  432 

radish,  342 

rice,  207 

tobacco,  600 
Windberry,  550 
Windsor  bean,  427,  429 
Wine  grape,  499,  500 
Wines,  502 
Wings,  415 

Winningstadt  cabbages,  332 
Winter  gourd,  615 

radishes,  243 
Wolberry,  550 
Wood,  30 

elements,  functions  of,  37 

fibers,  36 

parenchyma,  36 

strawberry,  364 
Woolly-podded  vetch,  429 
Wormwood,  625,  628 

Xanthoxylum,  475 
Xenogamy,  52,  95 


Xylera,  18,  36 

Yams,  SS6 
Yarrow,  625 
Yellow  egg  plums,  399 
-flowered  alfalfa,  447 
salsify,  635 
Young  dicot  stem,  33 
Yucca,  229 

Zanta  currants,  501 
Zea,  87,  157 
canina,  179 
mays,  158,  178 

amylacea,  178,  180 

amylea-saccharata,  178,  180 

curagua,  179 

everta,  178,  180 

hirta,  179 

indentata,  178,  180 

indurata,  178,  180 

japonica,  179 

key  to  "species  groups"  of,  180 

saccharata,  178,  180 

tunicata,  178,  180,  182 
ramosa,  179 
Zigzag  clover,  433,  441 
Zizania  aquatica,  206 

miliacea,  207 
Zygote,  52 


C^Onc^  -  9  c> 


This  book  is  a  preservation  facsimile. 

It  is  made  in  compliance  with  copyright  law 

and  produced  on  acid-free  archival 

60#  book  weight  paper 

which  meets  the  requirements  of 

ANSI/NISO  Z39.48-1992  (permanence  of  paper) 


Preservation  facsimile  printing  and  binding 

by 

Acme  Bookbinding 

Charlestown,  Massachusetts 


2006 


